In a large mixing bowl, whisk together the softened butter, olive oil and powdered sugar. Add in milk, tahini and egg. Whisk well. Add in flour and baking powder and stir with a spatula or use your stand mixer or just use your hand. You should get a soft and non-sticky dough at the end.

For the coating; in a small bowl, mix together the molasses and water. Put sesame seeds on a plate. Set these aside.

Put the dough on a lightly floured counter and roll it out.Cut it into rounds using a round cookie cutter.

Dip the round cookies first into the molasses and water mixture and then into sesame seeds. Make sure both sides are coated well. Place them on the prepared baking sheet.

Bake until golden brown. 

Let them cool on the baking sheet.