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 milk, Greek yogurt, and vanilla and mix to combine again. Set aside.
In a separate bowl, sift the flour, baking powder, baking soda, cinnamon, and nutmeg together. Add half of the flour mixture to the butter mixture and mix to combine. Add the rest of the flour mixture and mix until combined. Do not over mix the batter or else the cake will be tough.
Pour the cake batter into the greased spring-form pan. Sprinkle the sliced strawberries and rhubarb on 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 you have crumbles the size of peas. Sprinkle this mixture evenly across the top of the strawberries and rhubarb.
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.
Let the glaze harden for 10 minutes, then serve and enjoy!