In a small bowl, mix together the brown sugar, flour, cinnamon, and a pinch of salt. Add the cubed cold butter and, using your fingers or a fork, mix until you achieve a crumbly texture.

In a large bowl, whisk together the flour, sugar, baking powder, salt, and cinnamon.

In another bowl, combine the milk, egg, melted butter, and vanilla extract. Gradually pour the wet ingredients into the dry ones and stir until just combined—don't worry about a few lumps.

Heat a non-stick skillet or griddle over medium heat. Lightly grease it with a small amount of butter or oil.

Pour about ¼ cup of batter for each pancake onto the heated surface. Sprinkle a generous amount of streusel topping on each pancake while the batter is still wet.

Once bubbles form on the surface (approximately 2–3 minutes), flip the pancakes. Cook for another minute or two until golden brown.

Serve them warm with syrup, fresh fruit, or whipped cream.