Pre-heat your oven to 160C Fan/350F/Gas Mark 4 and grease two 6-hole donut tins with butter or a baking spread (or one 12-hole donut tin)
In a mixing bowl stir together the self raising flour and caster sugar. Add the crushed Oreos and mix in
In another mixing bowl or a jug, whisk together the milk, vegetable oil, vanilla extract and eggs
Pour the milk mixture into the flour mixture and whisk everything together until smooth and combined
Divide the batter between the trays. You can put the batter into a piping bag or a jug to make it a bit neater to dispense into the trays, 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
To decorate, set the donuts onto a cooling rack with a baking tray or some baking paper underneath to catch any drips
Make the icing by mixing the icing sugar, milk and vanilla extract together
Spread or pipe the icing onto the top and more rounder half of the donuts and place back on the rack to set
Top each donut with the chopped up Oreo pieces - the biscuits will go soft after being in contact with the donuts for a while so add them as close to serving as you can
Store leftover in an airtight container and eat within 3 days
Notes
Make sure your ingredients, particularly the eggs, are at room temperature before you start baking.
You can use a different type of oil besides vegetable oil. I'd recommend one that doesn't have a strong flavour, canola and sunflower oil would both work well.
The donut batter is very wet, so I recommend using a piping bag or a jug to pour it into the tin.
You will need a 12 hole donut pan (or two 6 hole donut pans) to make this recipe.
You could use any flavour of Oreo for this recipe such as mint, peanut butter or golden oreos. Or an alternative cookies and cream biscuit will also work.
Although I provide cup measurements, I highly recommend weighing your ingredients out using digital kitchen scales. It is the most accurate way to measure ingredients and will ensure the best results. Digital scales are very low cost and can be purchased for around £12 ($16.50).
For teaspoon (tsp) and tablespoon (tbsp) measurements, please use measuring spoons and not the type of spoons you eat with. Again this will ensure accuracy and provide the best results.