Orange Curd:Begin by making the orange curd, reserving egg whites and orange zest for the buttercream. Sprinkle powdered gelatin over orange juice and let sit for 3-5 minutes.
1/4 teaspoon powdered gelatin, 1/3 cup orange juice
Meanwhile, in small saucepan, combine egg yolks, sugar and butter. Heat over low heat until fully melted, whisking constantly.
75 g egg yolks, 150 g granulated sugar, 4 tablespoons unsalted butter
Pour in orange juice, continue whisking over low heat until curd is thickened and has reached 195°F.
Strain into a bowl and stir in salt.
1/4 teaspoon salt
Let chill in refrigerator for at least two hours, until mixture has thickened.
Vanilla Cupcakes:Preheat oven to 350°F. Prepare two cupcake tins with 16 cupcake liners. Sift together cake flour, baking powder and salt. Set aside.
240 g cake flour, 1 3/4 teaspoons baking powder, 1/2 teaspoon salt
In bowl of a mixer, cream together butter and sugar on medium-high speed until mixture is light and fluffy, approximately 5-6 minutes.
113 g unsalted butter, 248 g granulated sugar
Add oil and mix until thoroughly combined.
1/4 cup canola or vegetable oil
Add eggs one at a time on medium-low, mixing completely after each addition, scraping down the sides of the bowl as needed.
3 eggs
Add vanilla bean paste.
2 teaspoons vanilla bean paste
Alternating dry ingredients and milk, add 1/3 of the flour mixture on low. Once combined, add half the milk. Repeat until all ingredients are added, scraping down the sides of the bowl as needed.
1/2 cup whole milk
Slowly stir in the sour cream.
113 g sour cream
Scoop batter into prepared cupcake tins, filling liners 2/3 full.
Bake until cupcakes spring back to the touch, 18-22 minutes.
Orange Swiss Meringue Buttercream:In the bowl of a stand mixer, combine egg whites and sugar. 2/3 cup egg whites, 297 g granulated sugar
Place mixing bowl over a small pot of simmering water to slowly heat the egg whites.
Whisk constantly until the sugar is melted and egg whites reach 160°F.
Transfer mixing bowl to mixer. Whip on high until meringue forms and cools to room temperature.
Once cooled, reduce speed to low and add cubes of butter slowly. After all of the butter is added, return speed to high and continue whipping until butter is fully incorporated and buttercream is a light and silky texture. Do not be worried if the mixture appears to be curdled, this is part of the emulsifying process! This may take 10 minutes or so. (See recipe details above for troubleshooting if necessary.)
452 g unsalted butter
Add vanilla paste, orange extract and zest, and salt, mix until combined.
2 teaspoons vanilla bean paste, 1 teaspoon orange extract, Zest of 2 oranges, 1 teaspoon salt
Cupcake Assembly:Once cupcakes are cooled, and the orange curd is thoroughly chilled begin assembly. Using a sharp knife or cupcake corer, remove the center of the cupcakes. Do not cut through to the bottom. Reserve centers.
Fill cupcakes with approximate 1 tsp. of orange curd. If desired, take reserved center of cupcakes, slice 1/4" piece and replace on top.
Top with buttercream.
Optional: To make dehydrated orange slices: Slice oranges 1/8" thick and place on wire rack on baking sheet and bake at 170°F for 6-8 hours, turning occasionally. (These can be made in advance and stored in an airtight container!)