Stir oats, almond milk, yogurt, peanut butter, 2 tablespoons peanuts, maple syrup and vanilla together in a large bowl until combined. Refrigerate, covered, until slightly thickened, 30 minutes to 1 hour.
Stir chocolate chips and coconut oil together in a small microwave-safe bowl. Microwave on Medium, stirring every 20 seconds, until the chocolate is melted, 45 to 60 seconds; stir until the chocolate chips are completely melted and incorporated into the oil.
Divide the oat mixture among 4 (8-ounce) jars, about 1 cup each. Spoon about 2 teaspoons of the melted chocolate over each jar, tilting to cover the entire surface. Refrigerate, uncovered, until the chocolate layer is just set, about 10 minutes. Sprinkle with flaky salt and the remaining 1 tablespoon peanuts; cover and refrigerate until the oatmeal has thickened and the chocolate layer is fully set, at least 8 hours or up to 4 days.
