In a stand mixer, use the paddle attachment to blend the butter on medium until pale and fluffy. This will take about 2 minutes.
Turn off the mixer and scrape down the sides. Add in about half of the powdered sugar. Turn the mixer on low. Blend until ingredients are integrated and then turn the mixer off. Scrape the sides down again.
Add in the rest of the powdered sugar. Turn the mixer on low once again. Blend until ingredients are integrated and then mix on medium for 2 minutes. Turn off and scrape the sides down again.
Turn the mixer on high and mix for 3 minutes. The frosting will increase in volume.
Turn off the mixer and scrape down the sides. Add in the vanilla extract and 1 drop of Lavender essential oil. Mix on low and taste the frosting. If the lavender flavor is too light for your tastes, add 1 more drop of Lavender essential oil and blend again.
Now add a tiny amount of food coloring. Mix on low until the color is uniform. You might want to add more gel color for a darker, deeper shade. This might take a few sessions of mixing and scraping until all the color is consistent throughout.
Place the frosting tip into the decorator bag. Move the frosting to the bag and frost your cupcakes.