Time consuming: no.
I recently topped some chocolate cupcakes with toasted marshmallow butter that was incredible. It's reminiscent of nights around the campfire, complete with little bits of toasted marshmallows!!
Toasted Marshmallow Butter Cream
4 ounces (in weight) of marshmallows (about 16 large mallows)
1 cup of marshmallow fluff
1 cup powdered sugar (doesn't need to be sifted)
2 sticks of butter at room temperature
1/2 teaspoon of vanilla extract
1. Line a baking sheet with parchment paper. Place marshmallows (not fluff) on sheet and toast under the broiler. This will happen quickly so pay attention. A little brown toastiness is okay. Set aside to cool.
2. In a large bowl, beat the butter with a hand mixer on high until creamed. Decrease the mixer speed, add powdered sugar and beat, increasing speed until the mixture becomes fluffy.
3. Add toasted marshmallows, fluff, and vanilla extract, and beat until the frosting becomes light and airy.
4. Top on your cupcakes and enjoy. Or eat it straight out of your piping bag or bowl, I won't judge you.
**Note: if your toasted mallows are too warm when you add them to your butter/powdered sugar mixture it will be almost impossible to whip up a proper buttercream. Don't worry! Just set the bowl in the fridge for 5-10 minutes to help firm up the butter, take out, and whip as planned.
From Baking Me