Preheat your oven to 350 degrees.
In a medium sized bowl, mix together the flour, baking powder, salt, cinnamon, nutmeg.
In a large bowl, mix together the pumpkin, sourdough discard, buttermilk, vanilla, eggs, sugar, oil and maple syrup.
Add the wet ingredients into the dry ingredients.
Line a 9in x 9in with parchment paper and add the batter to it (I also like to use a round dish).
Make the crumb topping by adding the flour, sugar, cinnamon, and cold butter together. Mix until well combined.
Add the crumb topping and bake at 350 degrees for 35 minutes.
Make the glaze, start by browning the butter. Place the butter in a sauce pan and cook until the butter foams up and starts to turn brown. It will smell amazing, like hazelnuts. Let cool for 10 minutes.
In a separate bowl mix the powdered sugar and maple syrup. Add the browned butter. Mix well.
Remove the coffee cake from the oven. Let the cake cool for at least 20 minutes. Once the cake is mostly cooled add the glaze. Serve and Enjoy!