Grease the pot of your slow cooker and line the base with an oval of grease-proof paper.
In a bowl, stir together the flour, cocoa powder and baking powder.
150 g plain flour (all-purpose flour), 40 g cocoa powder, 0.5 tsp baking powder
In another bowl, cream together the butter and two sugars until light and fluffy.
115 g butter, at room temp, 75 g caster sugar (superfine sugar), 60 g soft dark brown sugar
Add the egg and vanilla extract and mix.
1 tsp vanilla extract, 1 egg
Stir in the dry ingredients.
It might look a bit dry but get your hands in and work it together so that it comes together like dough. When it is the right consistency the sides of the bowl will be clean.
Stir in the strawberries. I had to do this with my hands to mix them in.
75 g fresh strawberries
Also add the chocolate chunks and mix through.
100 g milk chocolate chunks
Press the mixture into the sc bowl, onto the grease proof paper. Press it into the sides so it is even.
Cook on low for around 3.5 hours. For the last half hour leave the lid ajar.
The sides will start to come away from the pot when it is ready, and the top will still look a bit moist, but it will harden on cooling.
Then take the pot out of the slow cooker and leave it to cool. When the pot is cool you can remove the cookie by turning the pot upside down and tapping on the bottom. Catch it on your hand then invert onto a cooling rack.