Streusel: 4 tablespoons (56g) cold unsalted butter, cut into pieces
Instructions
Preheat the oven to 350°F (175°C). Grease and flour a 9×13-inch pan or line it with parchment. Grate the zucchini on the medium side of a box grater. If it’s extremely watery, press it gently in a towel — don’t dry completely.
In a small bowl combine 1/2 cup brown sugar, 1/3 cup flour, 1 teaspoon cinnamon, and the cold butter. Use a pastry cutter or your fingertips to rub until it resembles coarse breadcrumbs. Chill in the fridge while you make the batter.
Whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg in a bowl.
In a large bowl beat the eggs with both sugars until combined. Add the melted butter, sour cream, and vanilla and whisk until smooth. It may look curdled briefly — continue.
Fold the dry ingredients into the wet just until combined. Fold in the grated zucchini gently. Do not overmix; a few streaks of flour are fine.
Pour the batter into the prepared pan and smooth the top. Sprinkle the chilled streusel evenly over the batter. Bake for 32–40 minutes until the top is golden and a toothpick inserted yields a few moist crumbs. If streusel browns too quickly, tent loosely with foil for the last 10 minutes.
Let the cake cool in the pan for 15 minutes, then slice and serve warm or cool completely on a rack. Store covered at room temperature up to 2 days, refrigerated up to 5 days, or freeze slices up to 3 months.
Notes
A tender, slightly tangy sour cream zucchini coffee cake with a cinnamon-brown-sugar streusel topping. Moist but not gummy, easy to make, and perfect for brunch or a cozy coffee moment.
