Preheat oven to 350. Grease a 9"round cake pan. Line with parchment paper and grease that as well.
Make the topping: In a saucepan, combine candies, sugar, food coloring and apple juice. Stir over high heat until candy dissolves. Add apples and
bring to a boil, stirring occasionally. Boil for 5 minutes. Place in the cake pan.
For the cake:Whisk the flour, baking powder, baking soda and salt together. In a large mixing bowl, cream butter and sugar until fluffy. Beat the egg yolks in one at a time, scraping bowl as needed. Beat in the sour cream and vanilla until smooth. On low speed(or by hand) stir in the flour mixture in three additions, scraping sides of bowl after each. Mix only until combined with no lumps. Do'nt over mix.Spread the batter over the apple mixture in the pan. Bake for 35-45 minutes until golden brown and toothpick comes out clean. Let cool 5 minutes on wire rack. Run a thin spatula around sides of cake to loosen, then invert onto serving plate. Leave pan in place for 1-2 minutes, then carefully lift off. If needed, remove parchment from apples.