Preheat oven to 350ºF and lightly butter an 8x8-inch baking dish; set aside.
In a large bowl, add flour, baking soda and salt; whisk until blended.
Add 3/4 cup butter and using a pastry cutter, combine with the flour.
Add brown sugar and rolled oats; stir until the mixture is crumbly (don’t over mix).
Scoop half of the flour-oat mixture into the prepared baking dish and, with the back of a spoon compact it by pressing down gently; set aside.
In a small saucepan, combine dates, water and vanilla extract. Stir and bring to a boil.
Reduce the heat to medium-low and gently simmer until the dates are soft, stirring often - while cooking, mash them.
Remove from the heat and cool off for about 5 minutes.
Spoon the date mixture on the bottom crust and level it out with a spatula.
Add the remaining oat mixture and press down gently.
Transfer to the preheated oven and bake for 25 minutes.
Remove from the heat and cool completely before cutting into squares.