Preheat oven to 350F and line a cookie sheet with parchment.
In a small bowl and a fork/whisk cream together butter and sugar until light and fluffy (took me a few min). Add cocoa powder, vanilla, and stir until no clumps remain. (Optional: also add a pinch of espresso powder to amp up the flavor)
In a mug/other bowl mix flour, baking soda, pinch of salt.
Gradually add dry to wet, stopping as soon as you get a nice soft cookie dough. If the dough gets too crumbly add a drop of water.
Fold in your crumbled halva, do not overmix so you still end up with chunks of halva. Make rounds between palms, place and flatten on the parchment.
Bake 12 minutes, cool for 5 and enjoy!
Notes
If you don't have a food scale, remember to use the spoon & level method in measuring flour to avoid over-measuring, which will lead to dry cookies.
If you don't have halva on hand (which is quite likely) just make this: 1 tsp tahini (or other nut/seed butter) 1 tsp maple syrup and add enough oat flour to turn it into a cookie dough consistency (about 1 tbsp, start with a pinch). Add a drop of vanilla and a pinch of salt to amp up the flavor. Set it for 5 minutes in the fridge/freezer then use as you would use the halva here. I'll bet it will work!