Preheat the oven to 180 degrees C/350F. Grease 10 holes in a cupcake tray.
Place the flours, bicarb and Peanut M&Ms into a medium sized bowl and mix together until combined.
Leave flour to one side. Place the butter and sugars into a large bowl or the bowl of your stand mixer. Beat until light and fluffy, about 2 mins on med-high speed.
Add in the eggs and vanilla.
Mix until well combined and smooth, scrape down sides as required.
Add in the flour and mix on a low speed until a dough forms.
Place 2tbsp of dough into each cupcake hole and flatten slightly with your fingers/the back of a spoon.
Place in the oven for 15-20 mins (mine took 15) until the edges are lightly browned.
Remove from oven and if you're using a metal cupcake tray, run a knife around the edge of each cookie cup.
Leave to cool in the tin before placing in an airtight container. Cookie cups will keep at room temperature for 4 days.
Notes
Recipe adapted from Table for Two - http://www.tablefortwoblog.com/2013/02/25/nutella-lava-cookie-cups/