Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4 and grease two 6-hole donut tins with butter or baking spread
In a large mixing bowl, stir together the self raising flour and caster sugar
In another bowl, whisk together the milk, vegetable oil, peanut butter and eggs
Pour the milk mixture into the flour mixture, and whisk together until combined
Divide the batter between the tins. You can put the batter into a piping bag or a jug to make it a bit neater to dispense into the tins, but you can do it with a spoon too
Bake them for 12 minutes, then remove them from the tin (I use a spoon to gently prise them out) and leave to cool on a cooling rack
Melt the milk chocolate in the microwave, make sure to use a microwave safe bowl. Heat the chocolate for 30 seconds, stir it, then heat in 10 second bursts, stirring in between
Set the donuts onto a rack with a baking tray or some baking paper underneath to catch any drips of chocolate
Dip the top half of the donuts in the milk chocolate and place back on the rack
Warm the peanut butter for 30 seconds in the microwave, put it in a small piping bag and cut a small amount off the end, drizzle it over the wet milk chocolate. Or you could drizzle with a spoon
Leave to set, or put them in the fridge to set the chocolate faster
Store leftover in an airtight container and eat within 3 days