Preheat oven to 350ºF. Line muffin pan with baking cups.
In large bowl, combine cake mix, sangria, orange juice, oil, and eggs. Blend with electric mixer on low speed 30 seconds. Scrape down bowl. Beat on medium speed 2 minutes. Add red color to achieve desired color. Fill cups 2/3 full.
Bake 18-20 minutes or until toothpick inserted into center of cupcake comes out clean. Cool cupcakes in pan on cooling grid 5 minutes. Remove from pan; cool completely.
For the filling: Combine all ingredients, except apples, in small saucepan. Cook on medium heat until very thick and just beginning to bubble, stirring constantly.
Stir in apples. Transfer to a bowl; press a piece of plastic wrap onto surface of filling to prevent a skin from forming. Refrigerate until chilled.
For the frosting: Bring sangria to a boil in a small saucepan. Simmer on medium heat until reduced to 1/4 cup liquid, approximately 10 minutes. Cool completely.
Beat butter and salt with electric mixer until smooth. Gradually add sugar, 1 cup at a time, beating well after each addition. Blend in orange juice. Gradually add chilled sangria, beating until well blended. Continue beating 2 minutes or until very soft and fluffy.
To assemble: Remove center of cupcake with coring tool or paring knife. Fill with prepared Filling using a pastry bag. Pipe Frosting onto cakes. If desired, garnish with additional thinly sliced apples.
*For Frosting, use any amount of sangria, as long as it is reduced to 1/4 cup