Soft and Fluffy Apple Pie Cupcakes with Cinnamon Frosting

Apple Cupcakes
1 Preheat your oven to 400°F and line a regular-size muffin tin with 15 cupcake liners. Lightly grease the cupcake pan to prevent sticking.
3 In a large mixing bowl, whisk together the sugar, vegetable oil, vanilla extract, buttermilk, and applesauce until fully combined.
2 Add the eggs, one at a time, mixing well after each addition to make a smooth cream mixture.
7 In a separate medium bowl, combine flour, baking powder, baking soda, salt, cinnamon, and all-spice. Stir to combine the flour mixture evenly.
6 Slowly add the dry mixture to the wet ingredients, mixing until just incorporated. Be careful not to overmix.
5 Using an ice cream scoop or large spoon, fill each cupcake liner about 2/3 of the way full with cupcake batter. Bake for 5 minutes, then reduce the oven temperature to 350°F and continue baking for 9–11 more minutes, or until the top of each cupcake springs back and a toothpick comes out clean.
4 Let the cupcakes rest in the pan for 2–3 minutes, then remove and cool completely on a wire rack.
Apple Filling
9 While the cupcakes cool, to make the apple filling: In a medium saucepan over medium heat, melt butter and stir in the chopped apples, brown sugar, cinnamon, lemon juice, and a pinch of salt. Stir frequently until the apples are tender. 
10 In a small bowl, mix the cornstarch with a tablespoon of water to make a slurry.
11 Pour the cornstarch slurry into the apple mixture and cook until thickened, then let cool to room temperature.
Cinnamon Frosting
13 To make the cinnamon buttercream, add softened butter to a large bowl or the bowl of a stand mixer fitted with a paddle attachment. Beat on medium-high speed until light and fluffy. 
15 Sift in the powdered sugar and mix on low speed. 
14 Add vanilla extract, salt, apple cider vinegar, and cinnamon. 
16 Once combined, beat on high speed for 1 minute until you have thick frosting with a smooth, pipeable texture.
Assembly
18 To assemble, use a cupcake corer or small knife to cut out the center of the cupcake, about 3/4 inch deep.
19 Spoon a bit of salted caramel sauce into the center of the cupcake, followed by a spoonful of the cooled apple filling. 
21 Fill a piping bag fitted with your favorite piping tips and swirl the cinnamon buttercream around the top of the cupcake, forming a ring. 
20 Add a final spoonful of apple filling to the center for a stunning finish.