Preheat the oven to 180C (350F) and grease your cake tins with butter. Line the bottoms with baking paper, grease and dust with flour, shaking out any excess.
Place the eggs in a bowl and use an electric hand whisk to whip them until light and frothy. Set aside.
Using a stand mixer, whisk the whipping cream until it holds soft peaks.
Add the whisked eggs and whisk together for 2 minutes. Gradually add the sugar and vanilla and keep whisking until well incorporated.
Sift the flour, cornflour, baking powder, matcha powder and salt into the batter. Use a large spatula to fold the dry ingredients, scraping along the sides and bottom of the bowl until the batter is smooth.
Divide among the prepared tins and bake 20-25 minutes, until the cakes are springy to the touch and coming away from the sides of the tins. Cool on a wire rack for 10 minutes and then carefully remove from the tins. Cool completely before filling and frosting.
To make the filling, put the mascarpone, icing sugar, double cream and vanilla extract in the bowl of your stand mixer. Start mixing on low speed to combine, then increase the speed to highest setting until you have firm peaks. Do not over mix.
Pipe a generous layer of mascarpone over the bottom cake layer and then scatter with a few sliced strawberries (optional). Repeat with the second layer, top with the third and add a thin layer of mascarpone over the entire cake as a crumb coat. Chill in the fridge while you prepare the frosting.
To make the matcha frosting, put the double cream in the bowl of your stand mixer. Sift in the icing sugar and matcha powder. Start whisking on slow speed to combine, then increase to highest speed until you have firm peaks.
Use a palette knife to smooth the matcha frosting over the entire cake. Drag the knife upwards to create little rustic finish on the cake and then top with fresh strawberries and edible flowers (optional). Best eaten soon after decorating.