Preheat the oven to 350F and line an 8x8 square pan with parchment paper.
To a small bowl, add the flour, baking powder, ground cinnamon, ginger, all spice, nutmeg and cloves. Whisk to combine and set aside.
In a medium bowl, combine the melted butter, sugar, room-temperature yogurt, and vanilla extract. Whisk together until well mixed, about 30 seconds to a minute.
Combine the dry ingredients with the wet ingredients, whisking until most of the flour is incorporated. Add the chocolate chips and roughly crushed graham cracker pieces, then gently fold them in until evenly mixed.
Spread the cookie batter evenly in the prepared pan, smoothing the surface. Layer the mini marshmallows evenly over the batter. Finish by sprinkling extra graham cracker pieces and chocolate chips on top of the marshmallow layer.
Bake the s'mores for 25 to 30 minutes; mine turned out perfectly at 28 minutes. It can be tricky to tell if they’re done due to the marshmallow but aim for them to be set with no jiggling, and the marshmallows should have a light golden-brown color.
Let the s'mores cool in the pan for 15 minutes before transferring them to a cooling rack. Once they reach room temperature, cut and serve. Store the s'mores bars in an airtight container at room temperature.