Preheat oven to 350F. Line a 9x9 baking pan with parchment paper. Set aside.
In a large bowl, combine oats, flour, sugar, baking powder, cinnamon, nutmeg, and salt. Toss in melted butter, yogurt, and vanilla with a fork until mixture is crumbly.
Reserve 1-1/2 cups of crumbled mixture for topping. Press remaining mixture in prepared baking pan in an even layer.
Bake crust at 350F 12-15 minutes until a very light golden brown. Set aside to cool for a moment.
Filling
In a large bowl, combine all filling ingredients. Spread in an even layer over baked crust and top with reserved crumble mixture.
Bake bars at 350F 30-35 minutes until topping is golden brown and filling is bubbly. Cool bars completely on a wire cooling rack.
Once bars are cooled, use parchment paper to lift bars from pan. Cut into squares and serve. Enjoy!
Notes
Storing InstructionsStore bars in an airtight container at room temperature up to 3 days.