In a small saucepan, combine water and butter for the dough. Heat until very warm (and butter is melted), to about 120-130 degree F.
In a large mixing bowl, add 1 cup of the flour, yeast, sugar, and salt. Add water mixture and blend together. Add in the cinnamon, nutmeg, maple and egg. Mix until well combined.
Add remaining 1 cup of flour and beat for about 2 minutes, scraping sides of bowl as needed.
Pour dough into a greased 8x8-inch baking pan. Cover with a clean, dry towel and let rise in a warm place until doubled in size (about 45 minutes).
While dough is rising, combine streusel ingredients with a pastry blender or your hands, until very crumbly. Set aside.
When dough is ready, sprinkle streusel evenly over the top. Bake in a preheated 350 degree F oven for about 35 minutes, until golden brown. Cool slightly on wire rack.
While cooling, prepare glaze. Whisk together the powdered sugar, milk and maple until smooth. Drizzle over warm cake. Slice and enjoy!
Notes
When heating the water and butter, do NOT overheat. I use a kitchen thermometer for this. You don't want to scald the yeast (because then it won't rise).
Once you've made the "dough" and pressed it into the pan, cover this with a clean kitchen towel and allow it rise for about 45 minutes.
While the dough was rising, I whipped up the streusel topping. You can use a pastry blender to cut in the butter, but I always find using my hands works best. You want to mix until it's "crumbly" with small pieces of butter still visible.
After baking, allow the cake to cool slightly before adding the glaze.
I recommend that you store it covered at room temperature for up to 3 days. Mine started to get a little stale by day 4, but I popped a piece in the microwave for 15 seconds, and it was perfect.