Pour whipping cream into a small pot. Remove rosemary leaves from sprig/stem and place into the pot with the whipping cream and cover the pot. Bring the pot to a slow boil and boil on medium-high for 1 minute. Remove from heat and let sit (and the rosemary seep) for 30 minutes. When the 30 minutes are up, drain the cream from the rosemary and set the rosemary aside for garnish.
Using a double boiler, melt chocolate, stirring frequently, until chocolate is all melted and smooth. When smooth, add the rosemary infused whipping cream and olive oil and stir until well combined.
Place chocolate in the fridge and allow it to sit and firm up for 1 1/2 - 2 1/2 hours, or until the chocolate is hard enough to work with, but not too hard. Using a cookie scoop (you can use your hands if you really want to...), scoop out the chocolate and place on a cookie sheet. Once all the chocolates are formed return to fridge to allow them to retain form.
Melt the remaining chocolate and gently coat the truffles and return to cookie sheet. Garnish with the reserved cooked rosemary and return to fridge and allow to firm. Serve at room temperature.