In the bowl of a standing mixer, whisk the egg yolks until they appear frothy and pale in color - this should take about 5 minutes total.
6 Egg Yolks
Add the corn syrup into a small saucepan, then cover with sugar. Heat on medium and stir gently until the sugar dissolves and the temperature reaches 238°F
¾ cup Granulated Sugar, ½ cup Corn Syrup
Immediately transfer the syrup to a glass measuring cup so that it does not continue to cook.
Pour a small amount of syrup over the egg yolks and whisk together. Stop the mixer and add the remaining syrup, then continue to whisk on high until the mixture cools to room temperature. This should take about three to five minutes.
Once the mixture has cooled, switch to using the paddle attachment. Slowly add your room temperature butter one tablespoon at a time while the mixer is running. Continue mixing on medium to high speed until the buttercream becomes light, aerated and smooth.
2 cups Unsalted Butter
To finish, slowly pour in the raspberry sauce and mix to combine! Take a moment to scrape the sides of your mixing bowl and mix for another 30 seconds before you've finished! You can use the buttercream right away on all kinds of cakes and desserts or store it in the fridge/freezer to use at a later time.
½ cup Raspberry Sauce