Preheat your oven to 180°C (350°F) and line muffin tins with paper liners.

In a medium bowl, whisk together flour, cocoa powder, baking powder, baking soda, and salt.

In a large bowl, mix melted butter, granulated sugar, and brown sugar until combined. Add eggs and vanilla, mix gently.

Gradually add dry ingredients to the wet mixture, alternating with buttermilk until just combined.

Fill muffin tins about two-thirds full and bake for 18-23 minutes. Check with a toothpick for doneness.

Melt chewy caramels and thickened cream over low heat until smooth, then cool slightly.

Beat softened butter and dark brown sugar until fluffy. Add caramel, vanilla, and salt, then mix in icing sugar.

Core the center of each cooled cupcake and fill with caramel filling.

Frost each cupcake generously with the buttercream and optionally drizzle with additional caramel or chocolate.