Coffee Cake with Cinnamon Streusel

Step 1: Grease and line a 20 cm (8-inch) square pan with baking paper, leaving an overhang so you can lift out the cake after baking.

Step 2: Preheat the oven to 160°C fan-forced or 180°C (350°F) in a regular oven.

Step 3: Put all the cinnamon streusel ingredients in a bowl. Using a handheld electric beater or a stand mixer with the paddle attachment, beat until the butter breaks into crumbs, about 20 seconds. Finish with your fingertips, rubbing the butter into the flour mixture until no pieces are larger than small peas. Refrigerate until needed.

Step 4: Whisk the flour, baking powder, and salt in a medium bowl, then set aside.

Step 5: Put the butter and sugar in a separate bowl. Using the same beater, beat for 1 1/2 to 2 minutes, until the butter is light and creamy. Beat in the eggs one at a time, then add the vanilla and oil. Beat until thoroughly combined.

Tip: There is no need to clean the beater before using it again.

Step 6: Add one third of the flour mixture and sour cream, then beat on the lowest speed until the flour is almost incorporated. Repeat twice with the remaining mixture. Finish with a rubber spatula until no flour is visible.

Tip: Finishing by hand helps avoid over-mixing and keeps the cake soft.

Step 7: Spread just over half the batter in the pan. Sprinkle 1 cup of the streusel evenly over it. Dollop the remaining batter across the surface and spread it to cover, working from the edges toward the middle. A small offset spatula is useful.

Tip: The bottom layer is slightly thicker so the cinnamon ribbon sits nearer the middle of the cake.

Step 8: Take handfuls of the remaining streusel and squeeze them in your fist to form clumps. Break the clumps into chunks and scatter them across the surface.

Tip: Use all the streusel; some will remain sandy, while the clumps add crunch.

Step 9: Bake for 40 to 45 minutes, or until a skewer inserted into the center comes out clean. Check the cake at 40 minutes.

Tip: Use the skewer test to check doneness.

Step 10: Cool in the pan for 15 minutes. Use the paper overhang to lift the cake onto a rack, then let it cool for another 30 minutes before adding glaze, if using. Slice to serve.

Step 11: Put the glaze ingredients in a bowl and whisk to combine. Use immediately, as the glaze forms a crust.