Prepare the Mugs : Lightly grease the inside of three microwave-safe mugs with a little oil or non-stick spray and set them aside.
Whisk the Dry Elements : In a small bowl, thoroughly whisk together the all-purpose flour, baking powder, pumpkin pie spice, and sea salt. This step ensures the leavening and spices are evenly distributed.
Create the Banana Base : In the medium mixing bowl, mash the ripe banana with a fork until it forms a smooth puree with only small lumps remaining.
Incorporate the Liquids : Pour the avocado oil, maple syrup, and vanilla extract into the mashed banana. Stir vigorously until the mixture is uniform and emulsified.
Unite Wet and Dry : Add the dry flour mixture to the wet banana base. Gently fold with a spatula until just combined and no streaks of flour are visible. Be careful not to overmix.
Fold in Add-Ins : Reserve one tablespoon each of the chocolate chips and pecans for topping. Gently fold the remaining amounts into the batter.
Portion and Microwave : Divide the batter evenly among the three prepared mugs. Sprinkle the reserved chocolate chips and pecans over the top of the batter in each mug. Microwave one mug at a time on high power for 90 seconds to 2 minutes. The cake is done when the center is set and a toothpick inserted into the middle comes out with a few moist crumbs attached.
Cool and Serve : Carefully remove the hot mug from the microwave. Allow the cake to cool for at least 4 minutes before serving, as the center will be extremely hot. Enjoy straight from the mug.