I am trying to make a lavender buttercream frosting and have already prepared the simple syrup, how would i incorporate and/or modify this recipe?...

I have used Lavender essential oil from dōTERRA for baking. They have good quality essential oils that I use for a multiple things besides cooking. But they are very powerful and u would only use a toothpick dipped into the oil first and then swirl into the frosting. One drop maybe too powerful depending on the quantity of frosting you are making.

When I make my lavender simple syrup for my Lavender Caramel Ice Cream, I start by buzzing the lavender flowers and the sugar in the food processor. This super-fines the sugar and integrates the lavender with it. I then strain the finished syrup and proceed with the custard for the ice cream. I would think you could do the same for your buttercream with ease.

Have you considered infusing the butter with lavender, then strain, re-chill to solidify, and use as normal butter? The way some people do with, ahem, pot? That way you won't have to deal with the added liquid that could break your buttercream.

Depending on the kind of buttercream you are making (French, Swiss or Italian), adding extra liquid, of any kind, can be tricky. The best way to add flavor to buttercream is to have it be dry, or a few drops of a food grade tincture. Think of your flavoring like vanilla extract.

I like to keep my buttercream simple, and add flavor to the cake, either by baking with herbs, or making a jam/syrup to soak into the cake layers. The latter is a trick oft used by professional cake bakers who have to freeze and defrost the cake a number of times while decorating, and for transport.

Lavendar is also challenging because too much and it's really bitter, too little - what's the point, and the buds are not really fun to eat.

What about making a lavendar ganache by infusing your cream with lavendar and pouring it over white chocolate. Taste the cream while you are infusing it, as much as is possible, and strain out the herb AS SOON as the flavor is strong enough.

If you're feeling adventurous, one of my favorite ways to work with herbs is to candy them. When they cool I put them in a spice grinder so I can add a pinch at a time until the desired flavor/scent is present.

You COULD but its a bit tricky. If I was infusing something like lavender into buttercream, where I'd really only want a whisper, I'd find lavender at your local spice shop, then rub the buds into the sugar to release some of the oils, then use that in the sugar syrup. You could so try throwing a handful into the sugar syrup after its done, quickly stirring it up, then straining them out before adding the syrup to the meringue...that sounds a bit tricky though since you really shouldn't loose temperature when making the syrup. Personally, I would invest in some high quality lavender extract.

Yes, lavender syrup is easy. Use unsprayed lavender flowers. Infuse in warm syrup for a while or grind up the lavender flowers (not stalks), and put in a sugar syrup. I've done both. Mix into your buttercream.

Lavender syrup is also good with gin & tonic.