Preheat the oven to 180C/350 F/Gas 4

Line the muffin tray with paper liners

In a bowl, whisk together, flour, cocoa, baking powder, bread soda, and salt

In a separate bowl mix the oil, sugar, milk , yogurt and vanilla

Add the wet ingredients to the dry and stir until just combined. Do not over mix

Stir in the chocolate

Spoon the mixture into the muffin tray dividing it between the twelve liners

Place half a teaspoon of the raspberry jam onto the top of each muffin. Swirl once with a toothpick or skewer

Bake for 19 to 22 minutes until the middles look set and a skewer comes out clean. Test at an angle to avoid the jam and be aware that jam may stick to the skewer

Let cool for 10 minutes in the tin and then transfer to cooling rack. Store in an airtight tin