Preheat the oven to 350 degrees F.
If using metal muffin tins, lightly grease them or line with parchment or silicone liners. Silicone muffin tins work best for easy removal.
Place one Ritz cracker into each muffin cavity.
In a medium saucepan, melt the butter over medium heat. Add the brown sugar and bring to a boil, stirring continuously. Allow the mixture to boil for 2–3 minutes, bubbling and caramelizing.
Remove from heat and drop a tablespoon-sized amount of the toffee mixture onto each Ritz cracker using a cookie scoop.
Place in the oven and bake for 8 minutes.
Remove from the oven and immediately top each Ritz with 1–2 tablespoons of chocolate chips.
Once the chocolate softens, spread it gently with the back of a spoon. If needed, return the tray to the warm oven for one minute to help melt the chocolate.
Top with Valentine sprinkles.
Place in the fridge to cool and fully set before removing from the muffin cups and storing in an airtight container.