Heat half-and-half along with the tea in a saucepan set over medium heat until simmering. Remove from the heat, cover, and steep for 30 minutes. Strain and pour into a liquid measuring cup to make sure there is 1/2 cup + 1 tablespoon. If not, add additional half-and-half or cream.

Place an oven rack on the middle shelf, then preheat the oven to 350 degrees F. Line three standard cupcake pans with 30 liners and spray lightly with baking spray. Note that one of the pans will have 6 empty spots. I recommend spraying from above with your arm at a distance to keep the spray from sending the liners flying. If you don’t have enough pans or you have an older oven that doesn’t cook evenly, these can be baked in batches.

In a medium-sized bowl, whisk together the flour, baking powder, and salt. In a separate medium-sized bowl, vigorously whisk the egg whites until frothy, 15-20 seconds. Whisk in the half-and-half and vanilla until evenly combined.

In a stand mixer fitted with the paddle attachment, cream the butter and sugar on low speed for 3-4 minutes, until the mixture has lightened in color and fluffed up slightly. Scrape down the sides of the bowl using a spatula.

Turn the speed to low and swiftly alternate between adding the dry and wet ingredients over 50-60 seconds, beginning and ending with the dry ingredients. Scrape down the sides of the bowl all the way to the bottom to catch hidden dry patches, then turn the speed to medium for 20-30 seconds to aerate the batter.

Divide the batter between the cupcake liners. Don’t fill the liners more than halfway up (when in doubt, less is more). Level the tops out (I like using a small offset spatula to do this). Bake for 25 minutes, or until the edges are golden brown, the tops are still slightly pale but firm, and a toothpick comes out clean from the center.

Let cool for 5 minutes, then carefully transfer to a wire rack to finish cooling (I use an offset spatula or butter knife to lift them out of the pan). Cool completely to room temperature before frosting.

In a small saucepan, heat the milk and lavender over medium heat, stirring briefly, until the milk in steaming and just starting to simmer. Remove from the heat, cover, and let steep for 45-60 minutes. Strain through a fine mesh strainer, discarding the lavender.

Place the sugar, water and corn syrup in a medium-sized saucepan (do not stir). Cover and turn the heat to high. Once the liquid begins to simmer and steam develops, remove the cover (this helps prevent crystallization). Using a digital or candy thermometer, cook the sugar to the soft boil stage, 235-240 degrees F.

While the sugar is cooking, whisk the eggs on high in a stand mixer fitted with the whisk attachment, until a soft peak has formed.

Turn the mixer speed down to medium-low and very slowly pour the syrup down the side of the bowl into the egg whites (this will “cook” the egg whites, making them safe to consume. Don’t pour the hot syrup directly into the meringue or you’ll have scrambled egg whites.

Once the syrup is completely incorporated, turn the speed to high. The meringue will continue to form a stiff peak as it cools down. Mix on high until the meringue comes to room temperature, approximately 15-20 minutes.

Once at room temperature, slowly begin incorporating the soft butter on medium speed. Once all of the butter has been added, turn the mixer speed up to medium-high and slowly add the vanilla and lavender-infused milk. You might not want to add all of the lavender, so start by adding half and see how you like the flavor.

If not using immediately, store the buttercream in an airtight container in the refrigerator, then bring to room temperature before using. Briefly whisk or place back in the stand mixer with the whisk attachment to make sure it’s nice and fluffy before frosting. Buttercream can also be frozen for up to 3 months (I like using gallon sized freezer bags).

To frost the cupcakes: Fill a piping bag halfway with buttercream, twist to close, and pipe decoratively. Serve cupcakes at room temperature. These are best served within 72 hours.