Beat first 2 ingredients at a low speed with an electric mixer until creamy. Gradually add sugar, beating until combined. Gradually add orange juice, beating at medium speed for 30 seconds or until frosting is spreadable. Beat at medium-high speed 30 seconds or until fluffy.

Preheat oven to 350° . Insert paper liners into 20 muffin cups. Set aside. Beat cake mix, 1 cup orange juice & next 4 ingredients at low speed with an electric mixer until combined. Scrape sides of bowl with a spatula & beat at medium speed for 2 minutes until batter is thick & well combined. Spoon about 1/3 cup of batter into each liner. Bake for 18-22 minutes. Brush tops of warm cupcakes evenly with remaining 2 tbs orange juice. Let cool in pan on wire rack for 5 minutes. remove from pan & cool completely. Spread about 1 heaping tbs of Marmalde Buttercream Frosting on each cupcake.