Line a baking sheet with parchment or wax paper, then top it with a cooling rack
Melt chocolate in whichever way you prefer (see my tips for perfectly melted chocolate in the green tip box right above the recipe).
If making multiple colors, divide chocolate between 2 or more bowls and stir in food coloring as desired.
Using dipping tools, or two forks, dip the Oreo cookies one at a time into the chocolate. Transfer cookie to the prepared cooling rack and top with sprinkles while chocolate is still wet. Repeat with remaining Oreo cookies.
Let set for about 30 minutes, or until hard. This can be done at room temperature, or in the refrigerator.
If drizzling the cookies, use either a fork to drizzle, or transfer melted chocolate to a piping bag (or ziploc) and snip a very small corner off. More sprinkles can be added on top of the drizzles if desired.
If at any point your melted chocolate starts to harden, it can be melted again.
Sprinkles and drizzles are beautiful, but optional, so feel free to make these however you desire.
Store in the refrigerator for up to 2 weeks in an airtight container.