How to Make It
Preheat oven to 350°F. Line an 8-inch square metal baking pan with parchment paper; let excess hang over edge.
Spread oats onto a baking sheet. Bake at 350°F until toasted, about 12 minutes. Place in a medium bowl; cool.
Place peanut butter, honey, and oil in a microwavable bowl. Microwave at high until warm, about 30 seconds; whisk until smooth. Whisk in vanilla, salt, and egg white.
Add pretzels and apples to oats. Pour peanut butter mixture over oat mixture; stir until well combined. Using a spatula, press mixture very firmly into prepared pan.
Bake at 350°F until lightly browned, 20 to 22 minutes. Cool in pan on a wire rack 15 minutes. Remove from pan using parchment paper. Cool completely on rack. Cut into 12 (4- x 1 1/3-inch) bars.