Cube the butter into a bowl and melt in the microwave or on the hob over a pan of water until just melted. Allow to cool until tepid but still liquid.
Add the soft brown sugar and whisk together.
Add the eggs and whisk until smooth.
Add the flour & baking powder. Mix together until smooth - the batter will be quite liquid.
Add the Mini Eggs and the white chocolate chips. Fold together.
Spoon into a lined baking tray and level off.
Bake for 24-26 minutes until firm at the edges and a little under in the centre - it will continue to set as it cools.
Allow to cool in the tin for 10 minutes, then carefully slide onto a wire rack to cool completely.
Top the blondies
Melt the chocolate in a microwave (in 30 second bursts) or over a bain-marie, stirring until smooth.
Drizzle the melted white chocolate on top of the cooled blondie.
Sprinkle the Mini Eggs on top and leave until set.
Slide the blondies onto a serving board and slice in 24 squares (in a pattern of 4 by 6).
Once the decoration on top of your Mini Egg blondies has set, you can cut them into squares and transfer them to a sealed container.You should be able to stack them on top of each other without much issue as the Mini Egg pieces will keep them separated, but it's a good idea to separate the layers with a piece of greaseproof paper to be sure.Keep the sealed container in a cool, dark spot, such as a cupboard or pantry and they should be good for up to a week.