Blueberry buckle with cornflake streusel

Combine the flour, brown sugar, salt and cinnamon for the streusel, work in the room temperature butter with your fingers until there are no dry spots and it holds together when squeezed.

Toss in the crushed corn flakes gently so they keep their texture and do not hydrate.

Butter the springform pan, line the bottom with a round of parchment cut to the same diameter, smooth out the air bubbles and butter the parchment.

Whisk the flour, baking powder, baking soda, salt and cornmeal together to break up lumps.

Cream the butter, granulated sugar and lemon zest with a hand mixer for a solid five minutes until very pale and aerated, with the butter at 68 to 70 degrees rather than warmer.

Beat in the eggs one at a time, scraping down the bowl frequently.

Add a third of the dry mixture on low, then half the buttermilk with the vanilla, then another third of the dry, then the rest of the buttermilk, then the last of the dry, mixing as little as possible.

Finish the last of the mixing by hand with a flexible spatula.

Fold in the blueberries gently so none of the berries burst.

Add the thick batter to the pan a dollop at a time to avoid air pockets, smooth the top and sprinkle the streusel evenly over the surface.

Bake at 350F for about an hour and a half to an hour 40 with fresh berries, or an hour 45 to nearly two hours with frozen, until a tester comes out clean.

Cool completely, at least two or three hours or overnight, then release the springform ring and slice.