1-First Step: Preheat and Prep Heat oven to 375°F. Line a 12-cup muffin tin with paper liners or grease well. This prevents sticking and eases cleanup. Gather all ingredients for mise en place, ensuring bananas are very ripe with brown spots for peak sweetness.

2-Second Step: Mash Bananas and Mix Wet Ingredients In a large bowl, mash 3 ripe bananas until smooth, about 1 cup. Stir in 1/2 cup melted butter (cooled slightly), 3/4 cup sugar, 1 egg, and 1 tsp vanilla. Whisk until combined. The mixture should look creamy. Tip: If bananas vary in size, measure mashed amount for consistency.

3-Third Step: Combine Dry Ingredients In a separate bowl, whisk 1.5 cups flour, 1 tsp baking soda, 1/4 tsp salt, and 1/2 cup crushed graham crackers. Breaking graham crackers into fine crumbs ensures even distribution. Avoid overmixing later to keep muffins light.

4-Fourth Step: Fold Wet and Dry Together Gently fold dry into wet with a spatula. Stir just until no flour streaks remain, about 10 strokes. Lumps are fine; overmixing toughens muffins. Batter will be thick from bananas.

5-Fifth Step: Add S’mores Mix-Ins Fold in 3/4 cup chocolate chips and 3/4 cup mini marshmallows, reserving 1/4 cup of each for tops. Distribute evenly for every muffin to have melty bits. Pro move: Chill batter 10 minutes if marshmallows melt too fast.

6-Sixth Step: Fill and Top Muffins Scoop batter into muffin cups, filling 3/4 full. Sprinkle reserved chips and marshmallows on top. Press lightly. This creates an inviting, golden crown.

7-Seventh Step: Bake to Perfection Bake 20-25 minutes. Rotate tin halfway for even browning. Toothpick inserted should come out with moist crumbs, not wet batter. Marshmallows will puff beautifully.

8-Final Step: Cool and Serve Cool in tin 5 minutes, then transfer to rack. Enjoy warm for best gooeyness. Pair with coffee or milk. Store extras as noted below. These chocolate muffins stay moist days thanks to bananas.