Preheat your oven to 325 degrees F. Spray 3 8 inch pans with cooking spray, line with parchment paper, and spray again, making sure to get the sides.
In a medium sized bowl, sift all of the dry ingredients (flour, baking powder, and salt).
In the bowl of an electric mixer, fitted with the paddle attachment, cream the butter, sugar, and Jell-O on high speed for about 3 minutes. With a rubber spatula, scrape down the sides and the bottom of the bowl. Beat again for 2 more minutes. The mixture will get lighter in color, which is what you want.
With the mixer on medium-high speed, start adding the whole eggs and egg whites one at a time, scraping after each addition, and still beating on high speed. I add an egg, beat for 30 seconds, scrape down the bowl, and repeat. After they have all been added, beat on medium speed for 2 more minutes.
With the mixer on the lowest speed, beat the sour cream, orange zest and the orange extract just until combined.
After you have added the sour cream and the orange extract, add the orange food coloring. Then add ⅓ of the flour mixture followed by half of the buttermilk. Mix just until combined and then add ⅓ of the flour mixture, followed by the rest of the buttermilk. Finish off with the rest of the flour mixture. With a rubber spatula, make sure to scrape the bottom of the bowl.
Pour about 17 ounces of cake batter into each of the prepared pans and with a small offset spatula or the back of a spoon, make sure to evenly spread the batter into the cake pans.
Bake for 30 minutes. Let them cool on the counter for 15 minutes and then let them finish cooling on a cooling rack.
After they have come to room temperature, wrap in plastic wrap and freeze before frosting the cake.
For the cream filling
In a medium sized mixing bowl, beat the cream cheese for about 2 minutes. Scrape down the bowl, and on medium speed, sprinkle in the granulated sugar, and add the vanilla extract.
In a chilled stainless steel bowl, whisk the heavy whipping cream until stiff peaks form.
With a rubber spatula, fold half of the heavy whipping cream into the cream cheese mixture. Then fold in the rest.
Store in an airtight container in the refrigerator until ready to use. This lasts 2 days while stored in an airtight container. I suggest making this filling right before stacking and filling your cake.
For the orange cream cheese buttercream
In a stand mixer fitted with the paddle attachment, beat the butter and cream cheese on medium-high speed until smooth, about 3 minutes.
With the mixer on low, add the powdered sugar until it’s all incorporated.
With the mixer on low, add the cream, vanilla and salt.
Turn the mixer to medium and beat the frosting for 3 minutes, or until it is light in color.
Use a wooden spoon to give it one last stir and push out the air bubbles.
Assembly
Level the cakes, if needed. Place the first cake layer, top side up, in the center of a cake board. Use a dollop of frosting to act as a glue, holding it to the cake board.
Spread half of the filling over the cake layer. Place the next cake layer with the top side up onto the cream filling. Apply the rest of the cream filling.
Place the final cake layer, with the top side down onto the cream filling.
Apply a thin coat of the orange cream cheese buttercream over the cake. This is the crumb coat. You'll then freeze the cake for 15 minutes to set the crumb coat and lock in the crumbs.
After the crumb coat is set, finish frosting the cake with the remaining buttercream.