In a large bowl, add flour, light brown sugar, baking powder, baking soda, ground cinnamon, and salt. Whick until combined and there are no lumps.
In a medium bowl, add milk, yougurt and eggs. Whisk until combined and pour into dry ingredients. Once combined it should be a medium batter.
Pour batter into the muffin tins and top with streusel. There will be a bunch of streusel and its recommended to push into the batter to get as much into the muffin as possible. I was able to get it all into the muffins but it takes a bit.
Bake for 15-18 minutes or until a toothpick comes out clean. Cool on a wire rach before serving.
Optional, but highly recommended - drizzle sweetened condensed milk on the muffins before serving.