Preheat the oven to 400 F (205 C). Line a 9 x 13 aluminum pan with parchment paper along the bottom and two longer sides. Leave some overhang of parchment paper. This will help the bars release from the pan more easily.
Place the pitted and chopped dates in a sauce pan. Top the dates with water, sugar and lemon juice. Stir well to fully disperse the ingredients in the pan. Cook the dates over medium - low heat for about 10 minutes or until the dates break down and start to incorporate in the sugar water. The mixture should resemble a chunky paste. Remove the pan from the heat. Stir in the vanilla extract. Cool the date mixture while making the oat crust and topping.
3 cups (454 g) Medjool dates, pitted and chopped , 1½ cups (360 ml) water, ¼ cup (50 g) sugar, 2 tablespoons (30 ml) lemon juice, 1 teaspoon vanilla extract
For a smoother date fulling, transfer the date filling to a food processor. Process the mixture to smooth. Return the filling to the same bowl. wipe out the food processor before making the oat crumble.
Add the flour, oats, light brown sugar, sugar, baking soda, cinnamon and salt into a food processor. Pulse the ingredients to combine. Add small cold cubes of butter to the mixture. Pulse again to work the butter into the dry ingredients. Continue to pulse the butter and dry ingredients together until a crumble texture forms.
1¾ cup (210 g) all purpose flour, 1½ cup (135 g) quick cooking or rolled oats, ¾ cup (150 g) light brown sugar, ¼ cup (50 g) granulated sugar, 1 teaspoon ground cinnamon, ½ teaspoon baking soda, ½ teaspoon salt , 1 cup (226 g) unsalted butter, cold and cubed
Press ½ of the oat crumble mixture into the prepared pan. Top the oat crust layer with the date filling. Top the date filling with the remaining ½ of the oat crumble.
Bake the date oat bars for 20 - 25 minutes. Look for a lightly golden brown crust. Cool the bars in the pan to room temperature or about an hour. If the bars are too soft to safely lift out of the pan, transfer the pan to the fridge to set for another 1 - 2 hours. Use the parchment overhang to gently lift the bars out of the pan, slice and enjoy.