Preheat your oven to 350 degrees F. Spray three 8-inch round cake pans with non-stick spray, line the bottom of each pan with parchment paper and spray again. Set aside.

In a medium size bowl, stir together the cake flour, salt and baking powder. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment, beat the butter, canola oil, and sugar on high until light and fluffy, about 5 minutes.

Add the eggs and egg yolks, one at a time to the bowl and beat on medium until well incorporated.

Turn the mixer on low and add half of the flour mixture to the butter mixture until fully incorporated. Then the sour cream and blend well. Finish by adding the remaining flour mixture and mix until combined.

Add the clear vanilla extract and butter extract and beat on low until incorporated. Scrape down the sides of the bowl and mix on low for another 30 seconds.

Evenly distribute the cake batter among the three pans and bake for about 23-28 minutes or until a toothpick inserted into the middle of the cakes comes out with just a few moist crumbs.

Remove cakes from the oven and let cool in pans for 10 minutes before inverting onto cooling racks to cool completely.

Puree the raspberries and lime juice in a blender. Strain the mixture through a fine-mesh sieve into a medium saucepan, pushing it through with a rubber spatula. Rinse the sieve - you'll be using it again.

Whisk the sugar, cornstarch, lime zest, and salt into the raspberry puree. Whisk in the egg yolk. Cook the mixture over medium heat, whisking constantly, until it's thick like pudding, about 5 to 7 minutes. Remove from heat and whisk in the butter a few pieces at a time until incorporated.

Strain the mixture through the sieve into a small bowl, pushing it through with rubber spatula. Press plastic wrap directly onto the surface to prevent a skin from forming. Refrigerate until completely set, at least 4 hours and up to 5 days. 

In the bowl of a stand mixer fitted with the paddle attachment, beat the butter until light and fluffy, about 2 minutes.

Turn the mixer to low and gradually add the powdered sugar, followed by the cream, salt and orange emulsion. Mix until combined. Add food gel, if using. Mix until incorporated completely.

Turn the mixer to medium-high and beat the frosting for about 5 minutes.

Remove bowl from the mixer stand and use a wooden spoon to beat the frosting by hand for about 2 minutes to push out any air pockets. 

Spread a small dollop of frosting onto a cake board. Place the first layer of cake, top side up, on the board.

Spread a thin layer of frosting over the cake layer and pipe a rim of frosting around the edge of the cake to create a barrier to the filling. Spread about 1/3 cup of the curd in the center of the cake, carefully spreading it to the edge of the piping.

Place a second cake layer on top of the piped frosting and filling and repeat step 2. Place the final cake layer, top side down, on the second layer of filling.

Lightly coat the cake with a thin layer of frosting to lock in the crumbs. Freeze the cake for about 10 to 15 minutes to set the frosting.

Finish frosting and decorating the cake with the remaining frosting.

The cake can be stored in the freezer for about a week, in an airtight container. Give the cake about 8 hours to return to room temperature before serving.