To make the crust place the butter into a large saucepot and heat over high heat. Stir often. After about 3 minutes, the butter will start to froth up and brown flecks will appear. Keep whisking and once the butter is medium brown, Lower the heat to low and stir in the milk powder, Equip and sweeteners if using.
Whisk the mixture well while gently heating. Whisk until the mixture is well combined. Remove from heat.
Allow to cool for a little bit, but while it is still liquid, pour into a parchment lined (otherwise it will stick) 8 by 8 casserole dish. Place in the fridge to set.
Once completely cool, remove from the fridge and cut into squares.