Preheat oven to 160℃ (fan-forced).
Line a lamington tin with baking paper. Leave enough paper hanging over the edges so that you can easily lift the slice from the tin once it's cool.
Melt the butter and honey in a small saucepan over a low heat, stirring until combined and set aside.
Combine the remaining ingredients in a large mixing bowl, then stir in the honey butter mixture, mixing until everything is combined.
Press the mixture firmly into the lamington tin, using a spatula or the back of a wooden spoon to smooth out the top.
Cook for 30 - 35 minutes until the slice is golden brown all over.
Allow the slice to cool completely before lifting it out of the tin. Cut the slice into bars and store in an airtight container for up to a week.