Brown 3/4 cup butter and cool until solid and no longer hot; then brown the remaining butter for the frosting and cool completely as well. The butter should foam, turn golden-brown, and smell nutty, with the color deep amber before you stop.

Preheat the oven to 350F and line cupcake tins. Make sure the liners are fully seated so batter bakes evenly.

Whisk all-purpose flour, baking powder, baking soda, chai spice blend, espresso powder, and salt together. Whisk until the spice blend is evenly dispersed and no dry pockets remain.

Beat the cooled browned butter and packed brown sugar until smooth and glossy, then add eggs one at a time. Beat in strongly brewed espresso, then mix in buttermilk and vanilla until the batter looks cohesive.

Fold the flour mixture into the wet ingredients just until no streaks of flour remain. The batter should be thick and smooth without overmixing.

Fill cupcake liners about 2/3 full and bake for 18-20 minutes. They’re done when the tops spring back lightly and a toothpick comes out mostly clean.

Cool cupcakes completely before frosting. Let them reach room temperature so the frosting doesn’t melt.

Beat browned butter chai frosting ingredients until fluffy: start with browned butter, then beat in powdered sugar and mix with milk to reach a pipeable texture. Beat until lighter in color and visibly airy.

Pipe frosting onto cooled cupcakes and dust with espresso powder and chai spice. Finish with a light, even sprinkle so the tops show a warm espresso-chai speckle.