Preheat oven to 350°F. Grease an 8-inch pie pan with butter or cooking spray.

Cream together butter and sugar using a mixer until fluffy (about 3 minutes).

Add eggs and vanilla. Mix well by hand.

Stir in cocoa powder, salt, and flour by hand until fully combined. Batter should be thick and glossy.

Pour into the prepared pie pan.

Bake for 30–35 minutes until the center is set. For a gooier center, remove closer to the 30-minute mark.

Let cool slightly and serve warm with ice cream or whipped cream.