- With the rack in the middle position, preheat the oven to 350°F (180°C). Line a baking sheet with parchment paper or a silicone baking mat.
- In a bowl, combine all the ingredients with an electric mixer until just moistened and forming pieces. Spread the mixture on the baking sheet.
- Bake for 15 minutes, stirring the crumble a couple of times until golden brown. Let cool.
- Store in an airtight container in a cold, dry place (see note).
- In a bowl, whip the cream with the sugar until stiff peaks form. Keep in the refrigerator until ready to serve.
- In a saucepan over medium heat, cook 2 cups of the berries with the sugar until they are hot and the sugar has completely melted.
- At the bottom of glass containers, divide the uncooked berries. Top with the stewed berries, crumble and whipped cream. Garnish with extra crumble, if desired.
Prep the crumble ahead of time and make assembly a piece of cake—it will easily keep for at least a week.