Preheat the oven to 180C / 350F / 160C fan forced. Grease and line an 8 or 9 inch spring form cake tin.
For the crumble place all ingredients except for the egg yolk into a bowl and use your fingertips to rub it together until the mixture looks like bread crumbs. Add the yolk and mix through with a fork. Refrigerate until required.
Sift together the flour and baking powder and set aside.
Beat together the butter and sugar until pale and creamy. Add the egg and vanilla and continue to beat until well combined. Add the flour, lemon zest and milk and mix until just combined. Make sure not to overmix.
Tip the batter into your prepared baking tin then spread to the edges and level out the top a little.
Dollop over the cherry jam, then scatter the crumble topping over the top of that.
Bake for 45 minutes or until a skewer comes out clean. Cool in the tin and then transfer to a wire rack to cool completely.
Lovely with a dollop of cream or icecream or, my favourite, served warm with some custard. Yum!
I use a standard Australian 20ml tablespoon (4 teaspoons worldwide)
For best results, you should always weigh ingredients like flour and sugar. Kitchen scales are relatively cheap but if you can’t weigh the ingredients, use the spoon and level method (don’t scoop).