Preheat your oven to 180°C (160°C for fan ovens) and line two large baking trays with baking paper.
Using an electric whisk or stand mixer, mix the butter, caster sugar and brown sugar together in a large bowl.
Add the egg and the vanilla extract and mix well until smooth.
Mix in the self-raising flour and when it starts to stick together, use your hands to press everything into a ball of dough.
Add the chocolate chips and gently knead them into the dough.
Divide the dough into 12 equal-sized pieces and roll each piece into a ball. Place the dough balls on your lined trays, making sure to leave a couple of inches between each cookie to allow space for spreading.
Bake the cookies for 11-12 minutes, until very slightly golden around the edges with a soft centre.
While the cookies are still warm, press M&Ms into them to create your bunny shapes.
Let the cookies cool completely on the tray then enjoy!