Exhibit 5.3

TreeHouse Foods, Inc.

2021 Spring Road, Suite 600

Oak Brook, Illinois 60523

Ladies and Gentlemen:

We have acted as special counsel to Sturm Foods, Inc., a Wisconsin corporation (“Sturm”), in connection with the preparation and filing by TreeHouse Foods, Inc., a Delaware corporation (the “Company”), with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Securities Act”), of (i) the registration statement on Form S-3 (File No. 333-248399) (the “Registration Statement”) filed with the Commission on August 25, 2020, (ii) the base prospectus dated August 25, 2020 forming a part of the Registration Statement (the “Base Prospectus”), (iii) the preliminary prospectus supplement filed pursuant to Rule 424(b) under the Securities Act on August 25, 2020 and (iv) the final prospectus supplement dated August 25, 2020 in the form filed with the Commission pursuant to Rule 424(b) under the Securities Act on August 26, 2020 (the “Prospectus Supplement” and together with the Base Prospectus, the “Prospectus”) in connection with the offering by the Company of $500,000,000 aggregate principal amount of 4.000% Senior Notes due 2028 (the “Notes”) and the related guarantees thereof (each a “Guarantee” and collectively, the “Guarantees”) by Sturm, Bay Valley Foods, LLC, a Delaware limited liability company (“BVF”), TreeHouse Foods Services, LLC, a Delaware limited liability company (“TreeHouse Foods Services”), Associated Brands, Inc., a New York corporation (“Associated Brands”), S.T. Specialty Foods, Inc., a Minnesota corporation (“S.T. Foods”), TreeHouse Private Brands, Inc., a Missouri corporation (“Private Brands”), American Italian Pasta Co., a Delaware corporation (“American Italian”), Linette Quality Chocolates, Inc., a Georgia corporation (“Linette”), Ralcorp Frozen Bakery Products, Inc., a Delaware corporation (“Ralcorp”), Cottage Bakery, Inc., a California corporation (“Cottage Bakery”), The Carriage House Companies, Inc., a Delaware corporation (“Carriage House”), Protenergy Holdings, Inc., a Delaware corporation (“Protenergy”), and Protenergy Natural Foods, Inc., a Delaware corporation (“Protenergy Natural”) (collectively, the “Subsidiary Guarantors”). The Notes and the Guarantees will be issued pursuant to the Indenture, dated as of March 2, 2010 (the “Base Indenture”), as amended and supplemented to the date hereof, by and among the Company, the Subsidiary Guarantors party thereto and Wells Fargo Bank, National Association, as trustee (the “Trustee”), and as further amended and supplemented by a supplemental indenture in the Form of Indenture, filed as an exhibit to the Registration Statement (the “Supplemental Indenture” and, together with the Base Indenture, the “Indenture”), and sold pursuant to the Underwriting Agreement, dated August 25, 2020 (the “Underwriting Agreement”), by and among the Company, the Subsidiary Guarantors and J.P. Morgan Securities LLC, as representative of the several underwriters named in Schedule 1 thereto.

We are members of the Bar of the State of Wisconsin, and we have not considered, and do not express any opinion as to, the laws of any jurisdiction other than the Wisconsin Business Corporation Law as in effect on the date hereof and we do not express any opinion as to the effect of any other laws on the opinion stated herein. Without limiting the generality of the foregoing limitations (and without expanding in any way any of the opinions that are set forth in this letter), we express no opinion regarding the legality, validity, binding effect or enforceability of the Guarantees or any other agreement or document.

This opinion letter is being delivered in accordance with the requirements of Item 601(b)(5) of Regulation S-K promulgated under the Securities Act.

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In rendering the opinions set forth below, we have examined and are familiar with originals or copies, certified or otherwise identified to our satisfaction, of, (i) the articles of incorporation of Sturm, as in effect on the date hereof, (ii) the Third Amended and Restated Bylaws of Sturm, as in effect on the date hereof, (iii) the Registration Statement, (iv) the Prospectus (v) the Indenture, (vi) the Underwriting Agreement and (vii) the Guarantee of Sturm. We have also examined originals, or copies certified to our satisfaction, of such corporate records of Sturm and other instruments, certificates of public officials and representatives of Sturm and other documents as we have deemed necessary as a basis for the opinions hereinafter expressed. In such examination, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals and the conformity with the originals of all documents submitted to us as copies. We have also assumed that each of the Company, BVF, Private Brands, Associated Brands, American Italian, Linette, Ralcorp, Cottage Bakery, Carriage House, Protenergy, Protenergy Natural and S.T. Foods is and will remain duly organized, validly existing and in good standing under applicable state law.

On the basis of the foregoing, and subject to the assumptions, qualifications and limitations set forth herein, we are of the opinion that:

The opinions expressed herein are subject in all respects to the following additional assumptions, qualifications, limitations, conditions and exclusions:

This opinion is rendered as of the date hereof, and we disclaim any undertaking to advise you of any subsequent changes in the facts stated or assumed herein or any subsequent changes in applicable law that may come to our attention, and we have assumed that no change in the facts stated or assumed herein or in applicable law after the date hereof will affect adversely our ability to

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render an opinion letter after the date hereof (i) containing the same legal conclusions set forth herein and (ii) subject only to such (or fewer) assumptions, limitations and qualifications as are contained herein.

This opinion has been prepared solely for your use and should not be quoted in whole or in part or otherwise be referred to, nor filed with or furnished to any governmental agency or other person or entity, or used, without our prior written consent.

We hereby consent to the filing of this opinion as an exhibit to the Company’s Current Report on Form 8-K filed with the Commission on August 27, 2020 and its incorporation by reference into the Registration Statement and to the reference to our firm under the heading “Validity of the Securities” in the Base Prospectus and “Legal Matters” in the Prospectus Supplement. In giving such consent, we do not concede that we are experts within the meaning of the Securities Act or the rules and regulations thereunder or that this consent is required by Section 7 of the Securities Act. In addition, we consent to Winston & Strawn LLP’s reliance as to matters of Wisconsin law upon this opinion letter in connection with the rendering of its opinion of even date herewith concerning the Guarantees, but only to the extent of the opinions specifically set forth herein. In giving these consents, we do not thereby admit that we are within the category of persons whose consent is required under Section 7 of the Securities Act and the rules and regulations thereunder.