Begin by preheating oven to 350°F (175°C) and place cupcake liners in baking pans.

Cream together 3/4 cup unsalted butter and 1 cup brown sugar on a high speed with a whisk attachment until the mixture becomes lighter in color.

Mix in 1/3 cup pasteurized egg whites or 3 large egg whites on a medium speed.

Sift 1 2/3 cups all-purpose flour, 1 1/2 tsp baking powder, 1/2 tsp salt, and 1 tsp cinnamon into the butter egg mixture and mix on a low speed until just combined. Scrape the sides of the bowl as needed.

Mix in 1/2 cup sour cream, 1/2 cup apple cider and 1 tsp vanilla extract on a low speed.

Fill the cupcake liners about 2/3 way full. Bake for 18-20 minutes or until a toothpick comes out clean.

Allow the cupcakes to cool for 10 minutes before moving them to a cooling rack to finish cooling. If you want to accelerate the cooling process, place the pan in your freezer for about 30 minutes.

Beat 1/2 cup of room-temperature butter on a medium high speed for 1-2 minutes with a whisk attachment until it becomes lighter in color and smooth.

Mix in 1 tsp vanilla extract, 2 tsp cinnamon, 1/4 tsp ground nutmeg, 1/4 tsp ground ginger and 1/4 tsp salt on a low speed.

Slowly add in 1 1/2 cups of powdered sugar, 1/2 cup at a time. Half way through add 1 Tbsp of apple cider to make the frosting easier to mix.

Mix on low for a couple minutes until the ingredients are fully incorporated and the desired consistency is reached. 

If the frosting is too thick, add in additional apple cider (1 Tablespoon at a time). If the frosting is too thin, add in more powdered sugar (1/4 cup at a time).

Melt 2 Tbsp unsalted butter in a large pan over medium heat.

Add 2 cups diced apples, 1/4 cup granulated sugar, 1 Tbsp lemon juice, 1 tsp cinnamon, 1/4 tsp nutmeg, 1/4 tsp ginger, 1/4 tsp salt, and 1/4 cup of apple cider and stir to combine.

Cook for 10-15 minutes and stir frequently until the apples have softened and the mixture has thickened.

Remove from heat and let the filling cool. Set aside.

Use a small knife or 1 inch circle cutter to remove the center from each cooled cupcake.

Fill each cupcake with a generous spoonful of apple filling.

Pipe a mound of spiced buttercream frosting on top of each cupcake using a large round piping tip. Chill the cupcakes in the fridge for 10 minutes or the freezer for 5 minutes to help the frosting firm up.

Add an apple chip or apple pie filling on top of the frosting as a garnish and enjoy!