For the cupcakes

1. Prepare your cupcakes according to your favorite recipe or package instructions. Allow cupcakes to cool.
2. Poke four holes in each cupcake with a chopstick or other round object.
3. In a small mixing bowl, stir together condensed milk and caramel sauce. Transfer this mixture to a piping bag or a zip top bag. You can just snip the tip off, but the mixture will be very runny. I highly recommend using a small round piping tip. Or if you have a squeeze bottle with a small tip, that could also work well.
4. Insert your piping tip or bag into each of the four holes in each cupcake and squeeze the mixture in. This can be very messy, so plan for drips.

For the frosting

1. In a small sauce pan over medium heat, whisk together flour and milk. Continue to whisk and heat until the mixture becomes thick like paste. Pop this into the fridge to cool for about ten minutes.
2. In a large mixing bowl, beat butter and sugar together on medium speed for about five minutes. You want the mixture to be very light and fluffy. Add the vanilla and beat to combine.
3. Add the milk and flour mixture, and beat on medium for another three minutes. Your frosting should be very fluffy, almost like whipped cream.
4. I used a Wilton 1M tip to pipe my frosting on. Hold the bag straight above the cupcake and squeeze for five seconds, then pull straight up. Or make an old-fashioned swirl.
5. Sprinkle with toffee bits or sprinkles.