Break up the chocolate and add it to a heatproof bowl with the condensed milk. Place the bowl over a saucepan of simmering water on low heat over the stove to create a double boiler.
Gently stir the mixture until the chocolate has fully melted. It should be thick and glossy.
Remove from the heat then add the lemon extract and yellow food colouring. Mix well.
Crush the meringues into small chunks and fold them into the fudge mixture, saving a small handful for topping. Transfer to your lined tin and press it evenly into place.
Top with the remaining meringue pieces and press them firmly into place so they stick fully.
Refrigerate the fudge for 4 hours until firm then cut into squares and enjoy.
Notes
Store in an airtight container in the fridge for up to 2 weeks.