Spray pan with nonstick baking spray and place strips of parchment paper in bottom of pan so the parchment extends over the four pan sides.
Prepare Date Filling
Chop dates into small chunks.
Place dates, water and granulated sugar in a medium-size saucepan.
Bring to a boil, stir often. Reduce to a simmer and cook until mixture is thickened, stirring occasionally (approximately 4 - 6 minutes)
Remove from heat and add the almond flour and vanilla. Stir until absorbed.
Set aside to cool completely.
Make Cookie Base
Preheat oven to 350° F
Sift or whisk together flour, baking soda and salt.
Place softened butter and brown sugar in the bowl of a stand mixer. Using the paddle attachment begin mixing on medium speed. Continue to mix until the butter and sugar mixture is light and fluffy (approximately 2 - 3 minutes). Note: a hand mixer may also be used.
Add the flour, baking soda and salt mixture. Mix for 20 - 30 seconds.
Remove the bowl from the mixer and mix in the oatmeal. Note: the dough will be crumbly.
Pour half of the dough into the bottom of the prepared pan. Using your hands, lightly press the dough down so it evenly covers the bottom of the pan.
Pour the date mixture over the dough in the pan and spread evenly.
Sprinkle the second half of the dough over the dates so it is evenly distributed.
Bake
Bake for 25 - 30 minutes. Cool completely before removing from pan.
Unmold by pulling up on sides of parchment paper and transfer to a cutting board. Remove parchment from bottom of the bar. Cut into desired shapes.