Combine 2 sticks butter, brown sugar, and granulated sugar

In a separate bowl, sift together flour, cornstarch, and salt

Combine flour mixture and butter mixture

Add beer and knead lightly until it all just comes together

Coat the bottom and sides of a spring form pan with remaining butter

Transfer dough to pan, press to evenly distribute

With a knife, lightly score 4 lines into the top into 8 equal pieces - like a pizza

Use a fork to lightly poke 3 times into the top of each piece

Chill in refrigerator at least 1 hour or cover and chill overnight

Heat oven to 350 and bake 30 - 35 minutes

Remove from oven and sprinkle with remaining sugar

Cool completely on a wire rack, remove outside of pan, cut into wedges where scored