Measure out Chex cereal into a large bowl. Note: if you're using the Strawberry Candy Melts, you'll use 4 cups of cereal. If you're using the white chocolate chips + pudding mix, you'll use 6 cups of cereal.
Pour chocolate into a small glass dish. Add 1/2 tsp shortening, if desired, to help the chocolate coat the cereal easier. Microwave for 1 minute 20 seconds. Let sit in the microwave for 3 minutes. Remove and gently stir. If chocolate loves its shape and looks smooth, it's done. If not, return to the microwave in 15 second increments, letting it sit for 2-3 minutes each time, until melted and smooth.
If you used White Chocolate Chips + Pudding Mix: Add 4 TBSP of the strawberry creme pudding into the white chocolate and stir gently until smooth. Add 2 drops of red food coloring, if desired.
Pour the chocolate mixture over the Chex cereal and stir gently to coat.
Transfer cereal mixture to a large piece of wax paper. Sprinkle with M&M's and Valentines sprinkles, if desired. Let cool to set. Break pieces and store in an airtight container to save. Candy can be made up to 3-4 days ahead, if desired. It saves well!