White Chocolate Ganache

• 10 ounces (283 grams) best quality white chocolate, finely chopped
• 2/3 cup (158 milliliter) heavy cream
• 1 1/2 tablespoons (3/4 ounce; 21 grams) unsalted butter, at room temperature and cut into 3 pieces

1. Put the chopped chocolate in a small heatproof bowl.
2. Bring the cream to a boil (you can do this in a microwave oven) and pour it over the chocolate. Let it sit for 30 seconds and then, using a whisk or heatproof spatula, gently stir the chocolate and cream together in small circles, starting in the center of the bowl and working your way out in ever-widening concentric circles. When the ganache is smooth, add the butter one piece at a time, stirring until it is incorporated.
3. If you're using the ganache as a filling for a tart or glaze, use it immediately. If you're using it to fill and frost a cake, you'll have to wait for it to thicken. You can leave it on the counter, stirring occasionally (it thickens slowly), or you can set the bowl into a larger bowl filled with ice cubes and water, in which case, stir often and stay close -- it thickens quickly. Alternatively, you can put it in the refrigerator, checking on it and stirring frequently. If you miss the moment, you can always reheat the ganache (see below).
4. Storing: The ganache can be covered tightly and kept in the refrigerator for up to 5 days or frozen for up to 2 months. You'll have to bring it back to the consistency you need before using it, either by leaving it out at room temperature or warming it. Heat it in 5-second spurts in a microwave or put it in a bowl set over a pan of simmering water. With ganache (especially white chocolate ganache), the keys to success are very low heat and a very light touch.

white chocolate, milliliter, unsalted butter

Taken from food52.com/recipes/31640-white-chocolate-ganache (may not work)