Line two baking sheets with parchment paper. Place the Mini Eggs in a sealed bag and crush them gently with a rolling pin, leaving a mixture of small pieces and larger chunks; reserve a portion for topping.

Beat the softened butter, light brown sugar, and caster sugar together until smooth, creamy, and evenly combined.

Mix in the beaten egg and vanilla extract until incorporated. Sift in the flour and bicarbonate of soda, add the fine salt, and mix only until a dough forms.

Fold in the chocolate chips and most of the chopped Mini Eggs, taking care not to overmix the dough. Divide it into approximately 18–20 portions and roll each portion into a ball.

Place the dough balls well apart on the prepared baking sheets. Chill the shaped dough for approximately 30 minutes to help reduce spreading and improve chewiness.

Preheat the oven to 180°C conventional, 160°C fan, or 350°F. Bake the chilled cookies for 10–12 minutes, until the edges are lightly golden while the centers remain soft and slightly underbaked.

Immediately press reserved Mini Egg pieces and a few chocolate chips into each warm cookie. Leave the cookies on the baking sheet for 10–15 minutes before transferring them to a cooling rack.