Preheat oven to 350 degrees F.
Cover two cookie sheets with non stick parchment paper. Set aside.
In a medium bowl, lightly beat the eggs, add sugar and whisk until light and fluffy.
Stir in peanut butter, vanilla and salt until well combined.
Using a spatula stir in the mini Reese's cups and peanut butter M&M's.
Using an ice cream scoop, or a regular spoon, scoop the mixture and form balls. Place them about 2 inches apart onto the baking sheets. Flatten the tops with the tines of a fork. The cookies should be about ¼ inch thick.
Bake until golden around the edges, about 12-14 minutes, switching the position of the sheets halfway through baking.
Cool on the baking sheets for 10 minutes, transfer cookies to a cooling rack to cool completely.
When the cookies have cooled melt the chocolate. Bring about an inch of water to a simmer in a saucepan. Set a heatproof bowl in the mouth of the pot, making sure the water doesn't touch the bottom of the bowl. Add the chocolate, let it soften for 1 min and stir until fully melted. Stir in corn syrup.
When chocolate is melted, remove bowl from heat, dip in the cookies half way, place on a baking sheet covered with parchment paper and decorate with sprinkles or chopped peanuts immediately.
Wait for chocolate to harden before serving.