Brown butter in small saucepan and allow to boil for a couple minutes. Remove from heat.
In mixer, beat melted butter with brown sugar for 3-4 minutes. Add salt and eggs. Beat in vanilla. Slowly beat in flour, baking soda and baking powder. Fold in the cashews and toffee bits.
Roll dough into one inch balls. Dough will be crumbly. Tap tops with fork or press with thumb, lightly.
Bake on parchment lined baking sheet in a 375 degree oven for about 8-10 minutes. Remove and enjoy.
Notes
While it’s not difficult to brown butter, you want to be careful not to burn the butter by accident.
To prevent this, I recommend using a pan with a lighter colored bottom so you can monitor the color of the butter better.
You’ll know the butter is ready when it turns a dark golden brown and smells nutty. When this happens, remove the butter from heat right away to avoid overcooking.
This usually occurs after about 2-3 minutes of boiling over medium heat on my stove.