Preheat your oven to 350°F (175°C). Spread pecans in a single layer on a baking sheet and toast for 6–8 minutes.

Brown the butter in a light-colored saucepan over medium heat until it turns warm amber and smells nutty.

In a medium mixing bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.

In a large mixing bowl, whisk together the browned butter and brown sugar. Add eggs, one at a time, whisking after each; follow with vanilla extract and sour cream.

Fold the dry ingredients into the wet mixture in two additions until just combined. Gently fold in the toasted pecans.

Line a muffin tin with cupcake liners and fill each about two-thirds full with batter.

Bake for 20–22 minutes, checking for doneness with a toothpick. Allow cooling in tin for 5 minutes before transferring to a wire rack.

Beat the softened unsalted butter until fluffy, then gradually add the caramel sauce and sifted powdered sugar.

Incorporate the heavy cream, vanilla extract, and salt until the buttercream is silky and holds its shape.

Pipe the caramel buttercream onto cooled cupcakes and garnish each with a toasted pecan half, extra caramel drizzle, and a pinch of flaky sea salt.