Heat oven to 350 degrees.

In a medium saucepan, melt butter over medium heat. As it starts to heat up, swirl the pan around often. Once it starts to bubble, let it deepen for 3-4 minutes.

Remove from heat and add brown sugar. Stir it for 1-2 minutes until the mixture is nice and glossy and all of the brown sugar is dissolved into the butter.

Let cool. It can be cooled at room temperature or can be put into the refrigerator for 10-15 minutes. It needs to be cooled to room temperature before adding the eggs. You don't want scrambled eggs!

Add eggs and vanilla and stir well.

Stir in flour, baking powder, and salt.

Before adding white chocolate chips, ensure the dough is chilled enough. You may want to put it in the refrigerator for a few minutes before adding white chocolate.

Stir in white chocolate chips and optional pecans.

Pour batter into pan of choice, smoothing top with a spatula.

Bake until top is shiny and slightly cracked approximately 20-24 minutes.

Let cool and cut into bars.