Preheat your oven to 350. Prep 4 - 8 inch cake pans with baking spray, and set aside.
Mix together the cake mix, pudding mix, milk, oil, and eggs included in the cake ingredient list above. Mix for 3 minutes on high-speed until the batter is well combined. Bake for 20-25 minutes, or until a toothpick comes out with moist crumbs on it. Your oven time may vary, so always start checking about 5 minutes prior to the listed bake time!
Remove the cakes from the oven and let cool for 10 minutes, and then remove from the pans to cook completely.
Mix together the cream cheese, milk, powdered sugar, vanilla, and instant pudding mix for about 4-5 minutes, until thickened and completely combined. Set aside.
Mix together the icing ingredients until well combined and fluffy, about 5 minutes. Mix in food coloring.
Once the cake is all the way cooled, take one of them and cut a large circle out of the middle, leaving about an inch and a half outside. Place first cake on your cake plate, and top with a generous layer of icing. Top with another cake layer and more icing. Place the ring of cake on top of the 2nd layer, and scoop in the filling mixture. Leave about a 1/2 inch on top. You may have a bit extra filling. Top the filling with half the blueberry pie filling.
Cut a thin slice from the top of the circle of the cake that you removed, and place that on top of the pie filling. Cover with more icing, and top with the final layer of cake.
Cover the cake with a crumb coat of icing, and chill for 45 minutes to an hour.
Remove from fridge and finish icing the cake. Smooth out as best as you can with an offset spatula.
Combine the lemon pudding accent icing ingredients and mix well for 4-5 minutes until smooth and set up. Start with 1 cup of milk, and add more little bits at a time until it is the thickness you prefer. I like my icing thick and pipable to hold the shape.
Place the icing into a piping bag with your favorite tip, and decorate as desired. Garnish with more pie filling.