In a large bowl, whisk together brown sugar, melted butter, eggs, and vanilla.
Whisk in flour, espresso grinds, baking powder, cinnamon, salt, ginger, cloves, chai powder, and pepper. Whisk in sour cream and milk until combined.
Spread batter into prepared pan. Sprinkle topping onto batter.
Bake until a wooden pick inserted in center comes out clean, about 30 to 35 minutes.
Let cool for a few minutes before serving.
Enjoy!