1. Beat first 3 ingredients at medium speed with an electric mixer until creamy.
2. Whisk together powdered sugar, cocoa, and malted milk powder. Gradually add powdered sugar mixture alternately with 3 Tbsp. milk, 1 Tbsp. at a time, beating at low speed until blended and smooth after each addition. Beat in up to 4 Tbsp. additional milk for desired consistency.