Beat butter and sugar till light and fluffy. Add the tahini and beat again Add the ground matzo and salt and beat well. Fold in 1/2 the chopped halva, cover and refrigerate till firm enough to scoop.

Line a baking sheet with parchment paper. Use a tablespoon or cookie scoop to drop rounds of dough onto your sheet, and top with the reserved chopped halva. Freeze till solid (the cookies can be close together at this point).

Pre-heat the oven to 325 degrees; line a second sheet with parchment paper and divide the cookies between both sheets (you should have about 11 - 12 cookies per sheet).

Bake cookies till golden brown around the edges, about 10 - 12 minutes. Let cool on the pan for at least 10 minutes, and then transfer to a wire rack to cool completely.