Ingredients
Equipment
Method
Prep and make the crumble
- Preheat the oven to 375F and line a 9x9 pan with parchment so the bars lift out easily. Make sure the parchment overhangs a bit for clean removal.
- Mix all-purpose flour, rolled oats, brown sugar, cinnamon, and salt together in a bowl until evenly combined. The mixture should look sandy and uniform.
- Add cold, cubed unsalted butter and cut it into the dry mix until large clumps and crumbles form. Stop when you can squeeze a clump that holds together.
Build and bake
- Press two-thirds of the crumble mixture firmly into the bottom of the prepared pan. Compress it as evenly as possible so the base bakes into a cohesive layer.
- Bake the base at 375F for 10 minutes until just set. Look for a light color change and a firm surface that doesn’t look wet.
- Toss the diced fresh peaches with granulated sugar, cornstarch, lemon juice, and vanilla extract until evenly coated. The peaches should look glossy and slightly thickened.
- Spread the peach filling over the warm base in an even layer. Keep the edges covered so the bars stay uniform when sliced.
- Scatter the remaining crumble evenly on top. The layer should look thick and mostly cover the peach filling.
- Bake at 375F for 25-28 minutes until golden. Use a visual cue: a browned crumble top and bubbling peach filling at the edges.
Cool and slice
- Cool the bars completely in the pan before lifting and slicing. The bars should hold their shape cleanly without crumbling.
Notes
For the cleanest cuts, press the base firmly and cool the baked bars fully before lifting—warm bars can crack as the filling is still setting. Store covered in the refrigerator up to 4 days; freeze sliced bars in a sealed container up to 2 months for longer storage. For a lighter crust, swap half of the butter with a neutral-oil baking alternative only if your recipe testing supports it; otherwise keep the butter for the thick, sandy texture.