Preheat oven to 350 degrees, Line a 9 x 5-inch loaf pan with parchment paper. Allow the paper to hang over the sides for easy removal
Sift all the dry ingredients into a large mixing bowl until there are no lumps. Stir 3 of the eggs in until the dry ingredients are moist (if needed later add the fourth egg)
Stir in the butter, yogurt and the extract until fully combined and a smooth, moist dough has formed
Scrape down the sides of the bowl and form the dough into a smooth ball. Massage the ball in hands for 1 minute to make sure of texture and absorb extra moisture. if the dough feels dry or not holding its shape then add the fourth egg if needed
Place dough back into the mixing bowl and allow to sit 5 minutes to absorb extra moisture.
After 5 minutes press the dough evenly into the prepared loaf pan and bake at 350 degrees for 30 to 35 minutes, until golden and a tester comes out clean
Remove from the oven. Immediately top spoon the marshmallow out 1 teaspoon at a time over the top of the blondie slab. As it melts spread the marshmallow until it fully covers the top of the blondie slab
If desired sprinkle the baking chips over the marshmallow. Allow the blondie slab to cool in the pan at least 1 hour to firm up. Cut into desired size pieces. Eat immediately or store leftovers in an airtight container at room temperature up to 3 days