3 1/2 cups (11 ounces) quick cooking oats
2 tablespoons (1 ounce) unsalted butter
28 each (7 ounces) marshmallows
1/4 cup honey
1/4 teaspoon salt
1 teaspoon vanilla
1/2 cup chopped peanuts
3 tablespoons creamy peanut butter
3/4 cup semisweet chocolate chips
Line bottom and two sides of 9- by 9-inch cake pan with foil, allowing foil to hang over edges of pan. Butter inside of pan.
In large skillet, heat oats over medium heat until lightly toasted and fragrant, stirring, about 5 minutes. Set aside to cool.
In large saucepan, heat butter with marshmallows over medium heat, stirring, until melted. Stir in honey, salt, and vanilla. Stir in oats until completely combined.
Transfer mixture to large bowl or sheet pan. Let cool to just barely warm (see note). Mix in peanut butter and chocolate chips. Press firmly into pan. Use bottom of measuring cup to smooth top. Let set, about an hour. Lift out of pan and transfer to work surface. Cut in half horizontally, then 5 vertical rows. Bars can be stored in a sealed container at room temperature for up to 1 week.