Pop popcorn using the desired method.
For stove-top, add three kernels of popcorn to a large pan. Add enough oil (a tablespoon or two) to come almost halfway up the sides of the kernels. Turn heat to medium-high.
When the kernels pop, add the rest of the popcorn, cover and shake continuously until there is a second (one-one thousand) between pops. Remove from heat and immediately pour one huge or two medium bowls. Sprinkle with salt and mix.
Add in the pretzels and mini-marshmallows and toss.
Melt chocolate in the microwave. Start with a one minute increment, then stir and place back in the microwave for 30 seconds. Remove and stir. If not melted, heat for another 30 seconds & stir. Repeat only until mostly melted then stir until completely melted.
Drizzle the chocolate over the mixture and mix well with a large spoon, spatula or clean hands. Sprinkle immediately with m&m’s. Spread out onto two large sheet pans lined with waxed paper, parchment or foil. Allow to sit until the chocolate has hardened, break apart.