Heat oven to 350 degrees F.
Grease a 13x9-inch pan with the 1 teaspoon of butter and 1 tablespoon of flour, or spray with cooking spray. Set aside.
Place macadamia nuts on a cookie sheet and place in oven for 10 minutes or until the nuts are fragrant.
In a large bowl, Cream butter and sugar together.
Add eggs and vanilla and beat until well incorporated.
In a separate bowl, combine flour and baking powder. On low speed, slowly add into the batter until dough is formed.
Gently fold in the white chocolate chips and macadamia nuts until evenly distributed throughout the dough.
Evenly spread dough in the greased 9x13 pan and bake at 350 for about 25 minutes, until set up but still moist in the middle.