Natural peanut butter (the oil rises to the top) is a healthier choice than the ones made with hydrogenated oil. You may also substitute another nut butter or a soy butter for the peanut butter.

1 ounce semisweet chocolate
1 ounce unsweetened baking chocolate
1 tablespoon unsalted butter
1/3 cup creamy peanut butter, preferably natural
2 tablespoons canola oil
1/2 cup firmly packed brown sugar
1/2 cup granulated sugar
2 large eggs
1 1/2 teaspoons vanilla extract
3/4 cup flour
1/4 teaspoon salt

Preheat oven to 325 degrees F. Butter an 8-inch square baking pan (or coat with nonstick cooking spray).

In a microwave-safe glass bowl, melt both chocolates with the butter on HIGH for 1 minute. Stir and cook another 30 to 60 seconds. Set aside to cool slightly.

In a medium-size bowl, beat the peanut butter and the oil. Add brown sugar and white sugar; continue beating until the mixture is light and fluffy. Add the eggs, one at a time, beating well after each addition. Mix in the vanilla extract, then the flour and salt until just combined. Stir 1/3 cup of the peanut butter batter into the chocolate mixture. Scrape the remaining peanut butter batter into the baking pan. Spoon the chocolate mixture over the batter. Using a table knife, make a zigzag through the layers to create a marbled effect. Bake for 30 to 35 minutes, or until a wooden pick inserted into the center comes out almost clean.

Cool in the pan, then cut into 16 bars. Store in an airtight container at room temperature.

Yields 16 servings.

Per serving: 153 calories; 7.3 g fat (2 g saturated fat; 43 percent of calories from fat); 20 g carbohydrates; 29 mg cholesterol; 67 mg sodium; 2.8 g protein; 0.9 g fiber