Separate the frozen berries if they’re stuck together. If necessary, strain them to remove any ice particles. Dry them with a paper towel. Add to a mixing bowl with the sugar, lemon juice, vanilla and cornstarch. Mix until combined. Add to your slow cooker.
In a separate mixing bowl, add the rolled outs, flour, brown sugar, cinnamon and salt. Mix to combine. Cut in the butter with a fork or pastry cutter. Pour on top of the berry mixture.
Place a paper towel on top of the slow cooker (prior to putting the lid on), then place the lid on top - there will be some overhang of the paper towel.
Cook on low for 3-4 hours, ensuring the berries have completely defrosted and the top is crispy. Keep on warm setting until you serve.
Serve with your favorite non-dairy vanilla ice cream or whipped topping.
