Preheat the oven to 325°F.
Grease an 8-inch spring form pan with butter. Set aside.
Using a hand blender or stand mixer, cream the butter and white sugar on high speed for 1 minute until fluffy. Add the egg and beat to combine. Add the vanilla and mix to combine again. Set aside.
Add half of the flour (1 cup) to the bowl, along with the baking powder, baking soda, cinnamon and nutmeg together. Mix until the batter just comes together.
Add the orange zest, Greek yogurt and milk to the batter and mix again until just combined.
Add the remaining 1 cup of flour and 1 cup of cranberries to the batter and mix again until just combined.
Pour the cake batter into the greased spring-form pan. Sprinkle the remaining 1 cup of cranberries on the top of the cake, making sure to get them evenly distributed. Press them slightly into the cake batter.
In a separate bowl, use your hands to crumble the brown sugar, flour and butter together until the flour is fully combined. Sprinkle this mixture evenly across the top of the cranberries and cake.
Bake the cake in the oven for 1 hour to 1 hour 15 minutes, or until a toothpick inserted into the center of the cake comes out clean. Once the cake is fully cooked, remove it from the oven and let it cool completely.
Once the cake has cooled, make the glaze. In a small bowl, whisk the milk and icing sugar together until smooth. Use a spoon to drizzle the glaze on top of the cooled cake in whatever pattern you like.
Serve and enjoy!