Heat the oven to 350°F. Line an 8-inch square baking pan with parchment paper, leaving an overhang on two sides.
In a large bowl, whisk together the sugar, flour, cocoa powder, baking powder, salt, cinnamon, cardamom, and espresso powder.
In a separate bowl, whisk the melted butter, vanilla, and eggs until combined. Pour into the dry ingredients and stir just until combined.
Fold in the ¾ cup walnuts. Spread the batter evenly in the prepared pan.
Bake for 25 minutes, until the top is set and a toothpick inserted in the center comes out with a few moist crumbs.
Cool in the pan for about 10 minutes. Use the parchment overhang to lift the brownies onto a rack and cool completely.
To make the glaze, whisk together the melted butter, cocoa powder, powdered sugar, salt, cardamom, coffee, water, vanilla, and honey until smooth.
Spread the glaze over the cooled brownies. Top with sprinkles and extra walnuts. Let the glaze set before slicing.