Preheat oven to 350 degrees Fahrenheit and spray an 8x8 baking dish with cooking spray.
In a large bowl, mix together the flour, both sugars, salt, baking soda and the unsweetened cocoa.
In a separate, smaller bowl, whisk together the yogurt, egg, milk and vanilla extract until smooth.
Add the wet ingredients to the dry ingredients and mix until just combined.
Using a spoon, stir in the pumpkin spice morsels.
Pour the batter into the baking dish and shake lightly to even out. Bake for 20 to 25 minutes or until a toothpick inserted into the middle comes out clean.
Allow to cool for 10 minutes before cutting into squares.