Preheat the oven to 180C/350F and spray a 12 hole muffin tin with cooking spray.
Place flour,s, bicarb, salt and chocolate chips into a medium sized bowl and stir until all the chocolate is coated in the flour. Leave to one side.
Place butter and sugars into a large bowl, or the bowl of your stand mixer and beat until light and fluffy, 2-3 minutes on medium-high speed.
Add in the egg and vanilla, scraping down the sides as necessary and mix on medium speed until well incorporated.
Tip in the flour mixture and mix on low-medium speed until a soft dough forms.
Place 2tbsp of dough into each prepared muffin hole and press down into the pan to create an even layer. Each hole should be about half full.
Press a mini Creme Egg into the centre of each cookie cup, pressing down to cover the first 1/4 of the egg.
Place in the oven for 12-14 minutes, until risen, lightly golden and still soft in the centre. The top will look matte in the light of the oven.
Leave to cool in the pan for 10-15 minutes and then transfer to a wire rack to cool completely.
Once cool, Creme Egg Filled Cookie Cups will keep in an airtight container, at room temperature, for 5 days.
You can serve them at warm temperature, or microwave them for 20 seconds before serving to make that centre ultra gooey!