Preheat your oven to 350℉. Cut a circle of parchment paper to line the bottom of your springform pan. Grease the pan and put the parchment paper on top of it.
In a sauce pan, melt the butter over low heat, then remove from the heat once fully melted.
10 Tbsp Butter
Add the sugar to the butter in the sauce pan and stir to combine. Add the eggs one at a time and stir to mix after each.
1⅓ Cup Sugar, 2 Eggs
Add the cocoa powder, flour, and vanilla to the mixture and stir until it comes together into a batter.
5 Tbsp Cocoa Powder, ¾ Cup Flour, 1 Tsp Vanilla Extract
Pour the batter into your cake pan and bake for 25 minutes. You're looking for a sticky, underdone-looking center rather than full brownie cooking.
Let the Kladdkaka cool fully before cutting and serving. Optionally, top with fruit, whipped cream, or a sprinkle of powdered sugar.