Preheat your oven to 350 degrees Fahrenheit (180 degrees Celsius). While it's heating up, line a cake pan or springform pan with some parchment paper. Butter the paper and dust the pan with flour. 

To make the topping, in a separate bowl, mix together the flour, sugar, and salt. Add the butter and use your fingers to combine everything until crumbs form. Put this aside.

In a small bowl, whisk together the flour, baking soda, baking powder, and salt. 

In your stand mixer bowl or a large bowl with an electric mixer, cream your butter and sugar together with some lemon zest until it's light and fluffy. This will take about five minutes. 

Add your eggs one at a time, beating for 30 seconds after each addition.

Add the yogurt, followed by the extracts and lemon zest. 

Add the flour mixture to the bowl all at once. Stir until it's just combined - don't overmix it.

Pour half of the cake batter into your prepared pan and scatter half of your blackcurrants on top. 

Spoon the remaining batter over the top and scatter the rest of the blackcurrants. 

Sprinkle the crisp topping evenly over the surface.

Put the cake into the oven and bake for 45-55 minutes. When it's golden brown and a toothpick inserted into the center comes out clean, it's done. 

Cool before serving. Enjoy!