To make the crumbs: In a medium bowl mix together flour, sugar, and cinnamon. Add butter and mix using a pastry cutter, fork, or your fingertips until the mixture is uniformly moistened and crumbs begin to form. Set aside.

To make the cake: Adjust oven rack to middle position and preheat to 340F/170C. Grease a 9-inch round cake pan. Set aside.

In a medium bowl mix together flour, baking powder, and salt until combined. Set aside.

In a standing mixer fitted with the paddle attachment, beat together butter, sugar, and lemon zest on medium speed until light and fluffy, about 3-4 minutes. Scrape down the sides and bottom of the bowl as needed. Add egg and beat until combined. Add half of the flour mixture and beat on low speed just until combined. Beat in heavy cream and vanilla just until combined, followed by the rest of the flour mixture. Do not overmix.

Scrape batter into prepared pan and smooth the top. Scatter raspberries evenly over the top of the batter (don’t press them in as they tend to sink during baking). Sprinkle crumb mixture over the raspberries.

Bake for 45 minutes or until cake is golden brown, firm to the touch, and a skewer inserted into the center comes out clean. If the top is browning too fast while baking, cover pan loosely with aluminum foil. Allow cake to cool completely on a wire rack. Serve at room temperature.

Cake can be kept, covered tightly, at room temperature or in the fridge for up to 3 days.