Preheat oven to 375 F/190 C. Butter and flour a bread pan.
Mix together topping ingredients until crumbly. Set aside.
Combine flour, flax meal, baking powder, and salt into a large mixing bowl.
Melt butter in a smaller bowl or quart measuring cup, then mix in sugar. Beat in eggs, then add milk and vanilla.
Add liquid ingredients to dry, and beat well. Pour batter into your prepared pan, then sprinkle the topping over it evenly. Bake at 375 F/190 C for 25-30 minutes, or until a toothpick inserted into the center of the cake comes out clean.
Let cool for about 10 minutes before serving warm.
Notes
Make this gluten free by using a one-to-one gluten-free baking flour.Adapted from The Spruce Eats.