Line a 12 x 14-inch tray with a silicone baking mat.

Add the butter to a large, heavy-bottomed saucepan or stock pot. Melt the butter.

Add the marshmallows, and continue stirring until completely melted.

Remove from heat. Stir in the sea salt and green gel food coloring.

Stir in the puffed rice cereal, and continue stirring until the mixture is well combined, with no dry cereal remaining.

Pour mixture onto prepared tray.

With damp fingers, press down the mixture until it is evenly distributed and about 3/4-inch thick.

Set aside and allow to cool at room temperature, at least 1 hour. Meanwhile, line a large tray, or two smaller trays, with silicone baking mats.

With a well-greased 2 1/2 – 3-inch shamrock cookie cutter, cut the slab into shamrock shapes. (Save the scraps for snacking!)

Transfer shamrock rice krispie treats to prepared tray(s).

In a microwave-safe bowl, melt the white chocolate in the microwave in short intervals, stirring periodically to prevent burning.

Transfer to a piping bag. Pipe white chocolate in zigzags over the shamrock rice krispie treats.

Sprinkle with rainbow sprinkles.

Dust with edible glitter.

Serve immediately.

Place leftover treats in an airtight container, layered between sheets of parchment. Store at room temperature for up to three days.