Prep the slow cooker: Lightly grease the bowl with butter or nonstick spray. For easier cleanup, line with a slow cooker liner or parchment.
Add the cherry layer: Pour the cherry pie filling into the slow cooker.
Stir in the vanilla, almond extract, and a pinch of salt to brighten the flavor.
Sprinkle the dry cake mix: Evenly sprinkle the cake mix over the cherries. Don’t stir. Keep the layer as level as possible so it cooks evenly.
Add butter: Drizzle the melted butter evenly over the dry cake mix, trying to moisten as much of the surface as you can.
A few dry spots are fine.
Add optional toppings: Scatter nuts, chocolate chips, or coconut over the top if you like a little crunch or extra sweetness.
Cook: Cover and cook on High for 2 to 2.5 hours or Low for 4 hours. The edges should be set and golden, and the center should be mostly cooked with a bit of gooeyness from the filling.
Vent to finish: If the top looks steamy, tilt the lid slightly or place a clean kitchen towel under it for the last 15–20 minutes to reduce moisture and help the topping crisp.
Serve: Spoon into bowls while warm. Top with vanilla ice cream or whipped cream.