Grease your bundt cake tin really well with butter and sprinkle the bottom with a little cocoa powder. Preheat the oven to 180 C (360 F). First we need to make the peanut butter filling.
Peanut butter filling
In a large mixing bowl add your peanut butter, cream cheese and caster sugar and beat with an electric mixer until smooth and creamy.
Add your vanilla, butter and egg. Beat again until combined.
Sift in your cornflour and stir through. Pop your peanut butter mixture into the fridge.
In a large mixing bowl, cream the butter and sugars with an electric mixer until pale, approximately 4 minutes. Add the vanilla extract and beat again.
Add one egg at a time and continue to beat until mixture is combined and creamy.
Boil the kettle and pour out 1/2 cup water and set aside.
In a separate bowl, sift the plain flour, cocoa powder, baking powder and baking soda and lightly whisk. Add the dry ingredients to the wet, along with the hot water and gently fold with a spatula.
Add the sour cream and fold until the mixture is completely combined and smooth. It will be quite thick - this is fine.
Grab your peanut butter mixture out of the fridge. Pour two thirds of the chocolate batter into your prepared bundt pan and the dollop the peanut butter mixture over the top, ensuring it doesn't touch the sides of the tin. Then dollop over the remaining chocolate batter and smooth the top - the peanut butter mixture should be completely covered.
Bake for approximately 45-50 minutes or until a skewer inserted into the middle of the cake comes out clean. Leave the cake to cool for about 30 minutes before very carefully removing from the tin and transferring to a wire rack to cool completely.
Meanwhile, make the chocolate ganache. Chop your dark chocolate into small pieces and transfer to a heatproof bowl. In a small saucepan, add your cream and pop on a medium heat.
Once the cream is warm but not boiling, pour the cream over the chocolate and leave for 2-3 minutes. Once the time is up, gently whisk the mixture until smooth. Leave to stand for a few minutes and then pop in the fridge for 30 minutes or so to thicken slightly.
Then pour the chocolate ganache all over your cake and sprinkle over your honey roasted peanuts.
Be careful when removing your cake from your bundt pan as the peanut butter will sink while cooking and may make the cake extra fragile. Grease your bundt pan really well and leave to cool before attempting to remove from the tin.