Preheat oven to 350°F/180°C. Butter and flour a 10-in. tube pan/bundt pan.
In a mixer using a flat paddle, cream the butter and sugar until fluffy, about 3 minutes. Add the egg and egg whites and mix until fully combined.
In a separate bowl, combine flour, baking power and salt. Set aside.
Add milk and vanilla extract to the egg mixture; mix until fully combined. (The mixture may have a curdled look but this is normal.)
Add dry ingredients and mix through until fully combined.
Add the chopped candy bits to the cake batter and fold in until combined. Pour into pan and bake 30 - 50 minutes; test with toothpick which should come out clean.
Cool and remove from pan; top with powdered sugar.