Line a 9x13 pan with wax paper or nonstick foil and set aside.
Put gelatin and Bailey's into the mixing bowl of a stand mixer with the whisk attachment and set aside.
In a medium saucepan, combine sugar, corn syrup, salt, and water. Cover and heat over medium high heat for 4-5 minutes.
Uncover, and attach your candy thermometer to your pot, heating until the mixture reaches 240° F (about 5 more minutes). See the blog post above for tips on using a candy thermometer.
Remove from heat. Begin whisking the gelatin mixture in the stand mixer. Very slowly pour in the syrup mixture while whisking.
Continue whisking for about 13 minutes (this is why you want to use a stand mixer!)
Remove bowl from mixer and using a greased spatula, stir in the Lucky Charms till well coated.
Spread mixture into the lined pan and let sit until the marshmallow has set.
Cut into squares and enjoy!