01 - Preheat the oven to 350°F. Grease and line a 9x5-inch loaf pan with parchment paper.
02 - In a large bowl, whisk together the flour, graham cracker crumbs, granulated sugar, baking powder, baking soda, salt, and cinnamon until evenly blended.
03 - In a separate bowl, beat the eggs with whole milk, vegetable oil, and vanilla extract until smooth.
04 - Add the wet ingredients to the dry mixture, stirring gently until just combined. Do not overmix.
05 - Gently fold in the mini marshmallows, semisweet chocolate chips, and 2/3 cup of the crushed pretzels.
06 - Transfer the batter into the prepared loaf pan and smooth the surface with a spatula.
07 - In a small bowl, blend melted butter, light brown sugar, 1/2 teaspoon cinnamon, and remaining 1/3 cup crushed pretzels. Sprinkle evenly over the batter.
08 - Bake for 45 to 55 minutes, or until a toothpick inserted in the center emerges with a few moist crumbs. Avoid marshmallow pockets during the test.
09 - During the last 10 minutes of baking, gently press additional mini marshmallows and a few chocolate chips onto the top if desired.
10 - Let the loaf cool in the pan for 15 minutes, then transfer it to a wire rack to cool completely before slicing.