Preheat oven to 350 degrees F. Line an 8x8 baking dish with foil.
Melt the butter and mix it with the flour, sugar, and salt until just combined. Don't overmix. Press into the bottom of prepared pan.
Bake at 350 for 30 minutes until the edges just start to turn golden. The middle will still VERY gooey, but the cake is definitely done at this point. Allow to cool completely before removing foil from pan and cutting into squares. Enjoy
These simple ingredients allow the flavor of the butter to really shine through. Since this cake is all about the butter, you’ll want to use a good quality butter. I decided to try it with a popular European-style butter — you can find this in just about any grocery store. Since European-style butter is higher in butterfat, it definitely gives the cake a rich, unique taste and silky texture.
However, believe me when I say you can use any kind of your favorite butter and this cake will be fabulous!! But if you’re making this for guests, and you want to really wow them and keep them guessing what the secret ingredient is, try making it with European-style butter.
Note: I used unsalted butter here, but if you want to use salted, just omit the salt in this recipe.