In a small saucepan, heat the heavy cream and butter over medium heat until just simmering. Remove from heat and add the finely chopped white chocolate. Let sit for 2-3 minutes, then whisk until smooth. Stir in the lemon juice, lemon zest, and vanilla extract until well combined.

Pour the lemon ganache into a mixing bowl and cover with plastic wrap, pressing it directly onto the surface to prevent a skin from forming. Refrigerate for at least 2 hours, or until firm enough to scoop.

Line a baking sheet with parchment paper or a silicone baking mat. Using a small cookie scoop or teaspoon, scoop out small portions of the ganache and roll them into balls between your palms. Place the truffles on the prepared baking sheet. Once all the truffles are formed, refrigerate them for another 30 minutes to firm up.

In a double boiler or microwave-safe bowl, melt the white chocolate and vegetable oil (if using) until smooth. Using a fork or dipping tool, dip each truffle into the melted chocolate, allowing any excess to drip off before placing it back on the baking sheet. If desired, sprinkle with additional lemon zest, yellow sprinkles, or powdered sugar while the coating is still wet.

Allow the coated truffles to set at room temperature or refrigerate for quicker setting.

Enjoy your Lemon Truffles chilled or at room temperature. Store any leftovers in an airtight container in the refrigerator for up to a week.