Line a small rectangular baking tray or cake tin with baking parchment. If you don’t have any, tin foil also works.
Break or chop the chocolate into pieces and place in a large microwavable bowl. Pour over the condensed milk and mix together well.
Pop the bowl into the microwave and heat in short bursts of around 30 seconds, taking it out and stirring in between, until the chocolate has almost melted. Be careful not to overheat.
Once the chocolate is melted, beat well with a wooden spoon until it all comes together smoothly. Add the vanilla extract and stir to combine.
Pour half of the mini eggs into the tray and spread around. Tip the fudge into the tin and spread around so it is in an even layer in the tin. Use a palette knife or spatula to smooth the top down. Scatter the remaining mini eggs on top of the fudge, pushing them into the fudge quickly before it sets.
Pop the tray of fudge into the fridge and leave to set for at least 2 hours or overnight. Once it has set hard, take it out and cut into pieces.