Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper to prevent sticking and set aside.
In a mixing bowl, combine 2 cups of flour, 1/2 cup of sugar, salt, and cubed cold butter. Use a pastry cutter or food processor to blend until the mixture resembles coarse crumbs with some pea-sized bits.
Press about two-thirds of this crumb mixture evenly into the bottom of the prepared baking sheet, creating a solid, press-in crust layer. Use the bottom of a glass or your fingers to smooth it out.
In a separate bowl, toss the sliced apples with lemon juice and cinnamon, ensuring they are well coated. Spread the apple mixture evenly over the crust, creating a generous filling layer.
Sprinkle the remaining crumb mixture evenly over the apples, covering the entire surface to create a crumble topping. Lightly press it down to help it stay put during baking.
Bake in the preheated oven for 35-40 minutes, until the top is golden brown and bubbling around the edges. The crust should be crisp, and the apples tender.
Remove from the oven and let cool slightly before slicing into bars. Serve warm or at room temperature, enjoying the contrasting textures of crunchy topping and soft, cinnamon-spiced apples.
