Mix flour, semolina, coconut powder, salt, and baking powder.
In another bowl combine eggs, milk, oil, sugar, vanilla, butter, and yogurt.
Whisk together well until no longer lumpy.
Add the wet ingredients on top of the dry mixture and fold until combined.
Add the tahini to your 9x13 tray and brush it evenly, making sure to get to the corners.
Pour the Basbousa batter and smooth the top.
Bake at 350℉ for 25-35 minutes or until a toothpick comes out clean.
Once out the oven, immediately pour simple syrup on top, about 2-3 cups of warm (not hot) syrup.
Let it cool completely at room temperature.
When it's time to cut, use a sharp knife, and wipe the knife after each cut in order not to ruin the shape. Make sure to cut carefully.