Preheat your oven to 350°F (180°C). To make the crust, mix together the flour, oats, nuts, and brown sugar in a medium bowl. Pour in the melted butter and mix until the mixture is well combined and crumbly. Press the mixture evenly into the bottom of an 8×8-inch square baking pan.

To make the filling, combine the dates, water, brown sugar, and lemon juice in a small saucepan. Bring to a boil, then reduce the heat to low and simmer for 10-15 minutes, or until the dates are soft and the mixture is thick and sticky. Spread the filling over the crust in the baking pan.

Bake the date squares for 25-30 minutes, or until the edges are lightly golden. Remove the pan from the oven and let it cool completely before cutting the squares into bars. Enjoy!