In a small bowl stir together the sugar, flour, and cinnamon until fully combined.
Add in the butter and use clean hands or a fork to break the butter up until the texture is sandy and there are no pieces of butter larger than a pea. Set in the fridge until you are ready to use it.
For Coffee Cake:
Preheat oven to 350 degrees (F). Spray a 9-inch round cake pan or an 8x8 square cake pan with non-stick spray and lay parchment paper in a cross shape across the bottom of the pan. Set aside.
In a medium bowl combine the flour, salt, baking soda, and baking powder.
In the bowl of a stand mixer fitted with a paddle attachment or in a large bowl with a hand mixer, combine the softened butter and sugar. Cream the two together until it is light and fluffy.
Add the maple extract and mix until combined.
Add the eggs one at a time, mixing well between each addition.
Alternate adding the dry mixture and the buttermilk, making sure each addition is just combined before adding the next. Stop mixing occasionally to scrape down the sides of the bowl.
Pour the cake batter into the prepared pan and top with the streusel mixture. Use a butter knife to swirl the cinnamon streusel into the cake batter.
Bake in preheated oven for 35-40 minutes or until a toothpick inserted into the center of the cake comes out clean.
Remove the cake from the oven and allow to cool while you prepare the glaze.
For Maple Glaze:
In a small bowl combine all of the ingredients and whisk until free of lumps.
Add more milk if the glaze is too thick.
Drizzle over the cooled coffee cake before serving.