Preheat your oven to 350°F (175°C) and prepare a 9x9-inch baking pan by greasing it or lining it with parchment paper.

In a large bowl, mix together the all-purpose flour, rolled oats, brown sugar, baking soda, salt, and ground cinnamon. Pour in the melted butter and stir until crumbly.

In a medium saucepan, combine the cranberries, granulated sugar, lemon juice, and vanilla extract. Cook over medium heat for 5-7 minutes until the cranberries burst and the mixture thickens. Remove from heat and let cool.

Press two-thirds of the crumble mixture into the bottom of the prepared baking pan. Spread the cooled cranberry mixture over the crust and sprinkle the remaining crumble mixture on top.

Bake in the preheated oven for 30-35 minutes until the top is golden brown. Allow to cool in the pan for at least 15 minutes.

For best results, chill in the refrigerator for an hour before cutting into squares.