Gluten-free coffee cake is a soft, tender cake with a buttery cinnamon crumb topping that makes it feel like the kind of bake everyone wants a slice of.
Preheat the oven to 350°F and grease an 8x8-inch baking dish or line it with parchment paper.
In a large bowl, whisk together the 2½ cups gluten-free flour, baking powder, baking soda, and salt.
In a separate bowl, whisk together the melted butter, honey, eggs, sour cream, milk, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and stir until just combined.
In a small bowl, mix together the ½ cup gluten-free flour, brown sugar, cinnamon, and melted butter until crumbly.
Spread half of the batter into the prepared baking dish, sprinkle half of the crumb topping over it, then add the remaining batter and finish with the rest of the crumb topping.
Bake for 30 to 38 minutes, or until the center is set and a toothpick inserted into the cake comes out clean.
Let the cake cool slightly before slicing and serving.