Buttercream Frosting
["1 c. milk", "3 Tbsp. flour or cornstarch", "1/2 c. butter", "1/2 c. shortening", "1 c. sugar", "1 tsp. vanilla"]
["Cook milk and flour or cornstarch until thick; let cool. Cream together butter, shortening, sugar and vanilla.", "Add flour mixture; beat 10 minutes."]
["milk", "flour", "butter", "shortening", "sugar", "vanilla"]