Creating the perfect Strawberry Rhubarb Crumble Bake is easy if you follow these simple steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C).
2. Prepare the Fruit: In a large mixing bowl, combine the sliced strawberries and chopped rhubarb. Add the granulated sugar, cornstarch, vanilla extract, and lemon juice. Toss gently to coat the fruit evenly.
3. Transfer to Baking Dish: Pour the fruit mixture into a greased 9×13 inch baking dish, spreading it evenly.
4. Make the Crumble Topping: In another bowl, combine the flour, rolled oats, brown sugar, melted butter, salt, and cinnamon (if using). Mix until crumbly.
5. Top the Fruit: Sprinkle the crumble topping evenly over the fruit mixture in the baking dish.
6. Bake: Place in the preheated oven and bake for 35-40 minutes, or until the topping is golden brown and the fruit is bubbling.
7. Cool: Remove from the oven and let it cool for about 10 minutes before serving.
8. Serve Warm or Cold: Enjoy it warm or at room temperature, perhaps with a scoop of vanilla ice cream or a dollop of whipped cream.

These straightforward steps will guide you in creating this incredible dessert that is sure to impress.