Preheat your oven to 180℃ (or 160℃ for fan ovens) and line an 8x8 tin with baking paper.
Add the butter, sugar and golden syrup to a large saucepan. Place over low heat on the stove and stir gently until the butter has melted and the sugar has dissolved.
Remove from the heat then mix in the oats. Then stir in the crushed Mini Eggs.
Press the mixture firmly into your tin and bake for around 18-20 minutes. The flapjack should be golden at the edges and will be a bit wobbly in the middle until it starts to cool.
Let the flapjack sit for 5 minutes then gently score with your knife where you plan to cut later.
Melt the milk chocolate then drizzle it over the flapjack. Sprinkle crushed Mini Eggs on top.
Leave to cool at room temperature for 2-3 hours to set, then remove it from the tin, cut into slices and enjoy!