Step 1

Preheat oven to 350 degrees F. Grease and flour a 9-inch springform pan or line a 9-inch square pan with a parchment paper sling.

Step 2

Cream the butter and sugar together in a large bowl until light, about 2 minutes. Add the eggs, lemon zest, and vanilla, mixing well to combine.

Step 3

Add the flour, baking power, and salt, mixing just until combined, then spread the thick batter into the prepared pan.

Step 4

Wash and slice the plums, then arrange them in a circular pattern on top of the cake batter, completely covering the batter and slightly overlapping.

Step 5

Prepare the streusel by mixing the flour, sugar, cinnamon, and softened butter in a bowl using a hand mixer for 1-2 minutes until it resembles crumbs. It should clump together if you give it a squeeze in your fist to make larger clumps of streusel. Sprinkle evenly over the plums.

Step 6

Bake for 45-55 minutes until golden brown and a toothpick inserted into the center of the cake comes out clean. Cool for at least 30 minutes before slicing and serving. This cake is delicious both warm with a scoop of ice cream or served cold from the fridge all by itself (my personal favorite).