Lemon Cupcake with Cream Cheese Frosting/Filling

For New Year's Eve, we went to my father-in-law's house. As usual, I brought a dish along. This time it was dessert.

I made these lemon cupcakes with lemon cream cheese frosting and filling.

Here's the recipe:
1 box (2 layer size) white cake mix (I used French Vanilla cake...I forget who makes it)
1 box (3.4 oz) instant lemon pudding
1 cup water
4 egg whites
2 tablespoons vegetable oil (I used canola oil)
1 package (16 oz. or 1 lb.) powdered sugar
1 package (8 oz.) softened cream cheese
2 tablespoons lemon juice

Mix cake mix, pudding, water, egg whites and oil together on medium for 2 minutes. The batter will be thick.
Line 2 cupcake tins with papers (I didn't have enough batter for 24 cupcake like the recipe calls for so make sure that you put water into any empty cups before baking so you don't burn the cupcakes).
Fill papers 1/2 to 3/4 full.
Bake 15-18 minutes at 350.
Let the cupcakes cool completely on a wire rack.
Mix the remaining ingredients together.
Fill a pastry bag with the frosting and insert the tip into the cupcakes, filling them with frosting.
With remaining frosting, use a knife to frost the cupcakes. (I added food coloring to the remaining frosting before putting on the cupcakes.)
Dip in sprinkles.
Enjoy!
Make sure to keep these bad boys in the fridge so the frosting doesn't spoil.