Preheat oven to 350 F and prepare an 8 inch round by lightly greasing.
Place the dates in a heat proof bowl. Boil some water, and add 1/2 cup to the dates. Set aside to let cool and soften, about 10 minutes. (Optional: once cooled, process the dates and water in a food processor to make smooth.)
Meanwhile, whisk together flour and baking powder in a separate bowl.
Using a hand mixer or a stand mixer, beat butter and sugars until light and fluffy. Beat in eggs, one at a time.
Add the date mixture, flour mixture, and vanilla extract, then mix until just combined and still moist. Pour batter into the prepared baking dish and bake until it passes the toothpick test, about 55 to 65 minutes.
Cool cake in pan on a wire rack for 5 minutes.
Serving options: 1) Slice the cake and pour sauce on individual pieces. 2) Remove cake from pan, but return it to the pan upside down (this prevents it from sticking as much to the bottom of the pan). Poke with a toothpick multiple times, then pour half or all of the sauce over it. Let it soak at least 20 minutes before slicing and serving. If there is extra sauce, pour some on fresh on the serving plate. Either way you have it, it's delicious with unsweetened whipped cream.