In a saucepan, melt the butter over medium heat. Whisk in the milk powder.
10 Tablespoons (142 g) unsalted butter, 2 Tablespoons nonfat milk powder
Continue whisking. The butter will begin to boil and then become frothy. Keep whisking until the butter turns brown. Remove from heat immediately. It will continue to brown as it cools.
Set the brown butter aside to cool until it reaches room temperature. You can pop it into the fridge/freezer if needed.
Using an electric hand mixer or a stand mixer fitted with the whisk attachment, whip the egg and egg yolk for 3 minutes on medium speed. The mixture should become frothy.
1 egg, plus 1 egg yolk
Add the brown sugar, granulated sugar, vanilla, and salt. Mix until just combined.
1/2 cup (100 g) brown sugar, 1/3 cup (67 g) granulated white sugar, 1 Tablespoon vanilla extract, 1/2 teaspoon salt
Add the cooled butter and flour. Mix until just combined.
1/2 cup (65 g) all purpose flour
Using a spatula, fold in the MOST of chocolate chips and pecans, reserving some for topping.
3/4 cup semi sweet chocolate chips*, 1 cup roughly chopped pecans
Spoon the filling into the pie shell.
1 9- inch pie crust, thawed/prepared according to instructions on package
Sprinkle the remaining chocolate chips and pecans on top of the filling.
Bake for 38-42 minutes. The crust and cookie should be golden brown and set. Allow the pie to cool for at least 30 minutes before serving. It should be warm and gooey.