1.5 cups AP flour
2 tsp baking powder
1/2 tsp table salt
1/4 tsp cinnamon
5 Tbsp butter
3/4 cup (packed) brown sugar
2 large eggs
1/3 cup canola oil
Grated zest of 1 lemon
1.5 tsp vanilla extract
8 small plums, halved and pitted

Heat oven to 350. Butter and flour an 8×8 baking dish. In a stand mixer, cream the butter and sugar together until homogenized, about 3 minutes. Add the eggs, one at a time. Continue beating, adding the oil, zest, and vanilla. Reduce mixer speed to low and add the dry ingredients, mixing until just combined.

Scrape the batter into the prepared pan and smooth the surface. Arrange the plum halves cut side up on top of the batter in a 4×4 grid. Press the plums into the batter.

Bake, and start checking for doneness at the 30 minute mark. Cake is done when the top has browned and puffed up around the plums, and when a toothpick inserted into the cake comes out clean. Cool on rack for 15 minutes, then de-pan. Cake may be stored for up to 2 days at room temperature.