Ingredients
Equipment
Method
- Preheat oven to 350°F (175°C) and position rack in the middle. Line an 8×8 inch (20×20cm) light-colored aluminum baking pan with parchment paper leaving 2 inches of overhang on two opposite sides. Lightly grease the two unlined sides.
- In a medium saucepan combine 3 cups (360g) raspberries, ⅓ cup (67g) granulated sugar, 2 tablespoons (16g) cornstarch, 1 tablespoon (15ml) lemon juice, and a pinch of fine sea salt. Stir to combine and cook over medium heat, stirring constantly, for 4 to 5 minutes until the mixture reaches a full simmer, turns deep ruby-red, and coats the back of the spatula thickly. Remove from heat and set aside to cool.
- In a large mixing bowl whisk together 1½ cups (180g) all-purpose flour, 1½ cups (135g) old-fashioned rolled oats, ¾ cup (165g) packed light brown sugar, and ½ tsp (3g) fine sea salt until evenly combined. Add 1 tsp (5ml) pure vanilla extract and stir through. Add ¾ cup (170g) cold cubed unsalted butter and rub into the dry ingredients using your fingertips until the mixture resembles coarse damp sand with no butter pieces larger than a pea and irregular clumps that hold when squeezed.
- Measure out two-thirds of the dough (approximately 360g) and press it firmly and evenly into the prepared pan using the flat bottom of a measuring cup. Press the edges slightly up against the parchment walls. Place the remaining one-third of the dough (approximately 180g) in the refrigerator immediately.
- Pour the cooled raspberry filling over the pressed base and spread into an even layer using a silicone spatula, taking it all the way to the edges with a ¼-inch margin at the pan walls.
- Retrieve the chilled crumble topping from the refrigerator. Scatter it in small pinches across the surface of the filling from about 2 inches above, working from the edges inward. Do not press it down.
- Bake at 350°F (175°C) on the middle rack for 35 to 38 minutes until the crumble peaks are medium golden brown and the filling is actively bubbling and deep crimson at the edges. Do not pull based on topping color alone — the filling must be visibly bubbling.
- Remove from oven and place on a wire cooling rack. Cool completely at room temperature for a minimum of 2 hours without disturbing. Transfer the pan to the refrigerator and chill for a further 30 minutes.
- Lift the bars from the pan using the parchment overhangs and place on a cutting board. Score the surface lightly into a 4×4 grid, then cut through using a sharp chef's knife wiped clean between every cut. Yield: 16 bars.
Notes
Use old-fashioned rolled oats only — instant oats dissolve into the dough and the texture becomes sandy with no visible oat structure.
Butter must be cold and cubed directly from the refrigerator — warm butter produces flat, sandy crumble with no distinct clumps.
Refrigerate reserved crumble topping immediately after mixing — even 10 minutes at room temperature softens the butter enough to collapse the clump structure.
Do not cut before the full 2-hour room temperature cool plus 30-minute refrigerator chill — the filling is still liquid beneath the surface for the first 90 minutes.
Cornstarch only — do not substitute flour or arrowroot. Flour produces a cloudy, pasty filling. Arrowroot breaks down at oven temperature.
Frozen raspberries work well — add directly from frozen, do not thaw. Filling will take 1 to 2 extra minutes to reach simmer.
Wipe the knife blade clean between every cut for sharp, defined edges — raspberry filling on the blade drags and tears the next cut.
Doubles cleanly to a 9×13 inch pan — increase bake time by 5 to 8 minutes, check at 40 minutes.
Allergens: contains gluten (wheat flour, oats), dairy (butter). Oats may contain cross-contamination with wheat depending on brand — use certified gluten-free oats if needed.
Make-ahead: bars are better on Day 2. Bake the evening before, refrigerate overnight, cut in the morning.
Freeze baked bars individually wrapped for up to 2 months. Thaw overnight in refrigerator — do not thaw at room temperature.