Preheat oven to 375* F

In a medium mixing bowl, whisk together the flour, sugar, baking powder and salt.

Cut the cold, cubed butter into the dry ingredients. I like to use my hands for this, but a fork or cut-in also work well. If you use your hands, push the butter into the flour with your fingers.

Combine the milk and egg together in a large liquid measuring cup or small bowl.

Pour the liquid mixture into the dry mixture and fold them together using a fork. Be patient and use a folding motion for maximum softness and fluffiness. Mix only until juuuuuust barely mixed. Overmixing will make the cake stiff.

Grease an 8X8 or 9X9 square pan.

Pour the batter into the pan and smooth gently, trying not to disturb the batter.

In another bowl, mix together the brown sugar, flour and cinnamon using a whisk or fork.

Cut in the butter the same as above, using your hands, a cut-in, or fork.

Sprinkle the topping over the batter.

For a fancier look, gently press the cinnamon sugar into the batter (but only just barely). Then use a knife and draw figure 8's through the batter. This will give it a more marbled looks and incorporate the cinnamon mixture down into the cake.

Bake at 375 for 25-30 minutes for a 9x9, or 30-35 minutes for an 8x8.  The edges will be lightly golden and a toothpick inserted into the middle will come out clean.

Serve warm and enjoy!