01 -
Set your oven to 350°F and give a 9x13 pan a good coating of nonstick spray.
02 -
Toss flour, sugar, baking powder, eggs, vanilla, and milk into a big bowl. Use a hand mixer to blend it all together. On low speed, drizzle in the melted butter. Mix just till it's combined and smooth. Pour the mix into the greased pan.
03 -
In a medium-sized bowl, stir together soft butter, brown sugar, flour, and cinnamon with a spoon until it's nice and creamy.
04 -
Scoop the cinnamon filling in little dollops over the batter. Grab a butter knife and swirl it together, twisting the knife through the batter till it’s marbled.
05 -
Bake the cake for about 35-40 minutes, or until you stick a knife in the middle and it comes out clean.
06 -
Combine powdered sugar, milk, and vanilla in a small bowl. Whisk until it’s smooth and runny.
07 -
Drizzle the glaze all over the warm cake, slice it up, and dig in while it’s still cozy!