Preheat oven to 350°F, and prepare a 9” springform cake pan with cooking spray and parchment rounds. In a medium to large sized mixing bowl, add the flour, baking powder, and salt, then whisk together to combine.

In a bowl, combine the lemon zest and sugar. Then, using your hands, rub the zest into the sugar until very fragrant.

In a stand mixer fitted with paddle attachment, add eggs, zest-sugar, elderflower liqueur and vanilla. Beat on high for around 5 minutes, the mixture should look thick, fluffy, and be tripled in volume. Then, slowly drizzle in the melted butter. After all the oil has been added, beat for an additional minute.

On low, add the dry mixture to the stand mixer in 3 additions, alternating with the sour cream in between. Beat only until the batter becomes smooth. Fold in 1 cup (190g) of blueberries.

Add the batter to the pan, then bake in the oven for around 50 to 60 minutes, or until a toothpick comes out clean. Allow cake to cool completely before topping.

In a stand mixer fitted with whip attachment, add heavy cream, confectioners sugar and vanilla. Beat on high until just before stiff peaks form. Add in the mascarpone cheese, then beat until well-combined and stiff peaks have formed.

Dollop the mascarpone whipped cream on top of the cooled cake, then top with remaining 1 cup (190g) of blueberries. Dust with additional confectioners sugar and serve.