Preheat the oven to 350 F and place a rack in the middle of the oven.

In a medium bowl add in the sugar and lemon zest. Rub the zest into the sugar with your fingers until fragrant and the sugar begins to clump.

Pour in the flour, baking soda, baking powder, and salt and whisk to combine.

Add in the butter, yogurt, eggs, and vanilla.

Use the paddle attachment to mix the ingredients first on medium low until just combined, then turn it to high speed for 30 seconds.

Scrape the sides and bottom of the bowl.

In a separate bowl, stir together the blackberries and 15 grams of flour. Pour the flour coated berries into the cake batter and use a spatula to fold them in.

Spray the cake pan with your baking spray and then pour in the cake batter.

Smooth out the cake with a rubber spatula.

Bake the cake in the preheated oven for 30 minutes. After 30 minutes, rotate the cake 180 degrees and bake for another 20-25 minutes.

When the cake is finished baking, check it by sticking a toothpick into the center of the cake. If the toothpick comes out clean, the cake is fully baked.

Remove the cake from the oven and leave it to cool for 10 minutes before removing the spring form.

After 10 minutes, remove the springform.

Allow the cake to cool completely before assembling.

Add the blackberries (fresh or frozen) into a medium bowl, along with the sugar and lemon juice.

Stir to combine and leave at room temperature to macerate until ready to use. If you are making them the day before, place them in the fridge overnight.

In a large metal bowl or the top portion of a double boiler, add in the egg yolks, sugar, salt, lemon zest and lemon juice. Whisk to combine.

Add about 2" of water into a sauce pan or the bottom of the double boiler. Bring to a simmer and then reduce the heat to low so that it maintains a simmer.

Place the bowl with the egg and lemon mixture over the pot of simmering water. Whisk constantly, cooking the mixture until it thickens. It's done when the mixture is thick like mayo.

Once thick, immediately remove the bowl from the pot of water and turn off the heat.

Add the cold mascarpone into the hot curd, one spoonful at a time. Whisk one spoonful of mascarpone into the lemon curd until completely dissolved before adding in the next spoonful.

Continue adding the mascarpone in until it is all used up. Pour the mixture into a large shallow bowl and place a piece of plastic onto the surface. Place the bowl in the fridge until cold and thick.

Once the lemon curd mixture is cold and set, spoon about 75 grams into a small bowl and set aside.

In a large bowl, whip the cold heavy cream on medium high speed until almost stiff peaks form. Be careful not to over whip the mixture.

Add half of the whipped cream into the lemon curd and fold to combine. Then, add in the other half of the whipped cream and fold until combined.

Optionally, level off the domed top of the cake first with a serrated knife.

Slice the cake into 2 layers with a serrated knife.

Place the bottom layer of the cake onto a dish or cake stand, ideally lined with parchment for easy transportation.

Scoop half of the lemon curd whip onto the bottom layer of cake and spread it out.

If fresh blackberries were used, mash half of them in a separate bowl with a fork for the middle filling.

Scoop half of the macerated blackberries out of the bowl, leaving as much of the liquid in the bowl as possible. Sprinkle the blackberries over the whipped cream.

Layer the top layer of cake over the frosting and press down gently.

Scoop the remaining whipped cream onto the top of the cake, using the back of a spoon to make loose swoops on top.

Spoon the extra lemon curd mixture around the top of the cake and swirl them in.

Spoon the remaining macerated blackberries onto the whipped cream and lemon curd.

If time allows, leave the cake to firm up slightly for an hour or two in the fridge before slicing.