Position a rack in the center of the oven and heat the oven to 350°F.
Grease and flour one 9x5x3- inch loaf pan.
In a medium bowl, whisk together the flours, baking powder, and salt. Set aside.
In the bowl of your mixer, beat the sugar and peanut butter until well combined.
Add the eggs, one at a time, beating until incorporated.
Mixing on low speed, add half the flour mixture, then half the milk, mix until blended and then repeat by adding the rest of the flour and milk. Mix until all the flour is incorporated, scrape the bowl and then continue mixing until batter is smooth.
Stir in the chocolate chips by hand.
Pour the batter into the greased loaf pan.
Bake until the loaf is golden brown and a toothpick inserted into the loaf comes out clean, about 50 to 55 minutes.
Cool in the pan on a rack for 15 minutes and then turn the loaf out unto a wire rack to cool.
Notes
Whole wheat pastry flour can be substituted with all-purpose flour.
The loaf can be frozen for up to three months. Wrap loaf with plastic wrap and place in a freezer bag. Thaw overnight in the refrigerator.