Heat oven to 350 degrees and line a 12-cup muffin tin with paper liners.

Prepare the cupcakes: In the bowl of a stand mixer fitted with the paddle attachment (or in a large bowl), combine the flour, granulated sugar, baking powder, baking soda and salt. Stir to combine. Add the butter and mix on low until the mixture is sandy and the butter is evenly distributed.

In a large measuring cup, whisk to combine the buttermilk, eggs, oil and 1½ teaspoons vanilla extract.

Add half of the buttermilk mixture to the bowl of the mixer and mix on low until incorporated, then add the second half of the mixture and mix on low until well combined. Scrape the bottom and sides of the bowl, then turn the mixer up to medium speed and mix for 30 seconds, until the mixture is smooth. The batter will be loose.

Divide the mixture among the prepared liners. (They will be about halfway full.) Bake the cupcakes for 18 to 20 minutes until just cooked through with little to no browning on top. Set the cupcakes in the pans on cooling racks for 5 minutes, then gently remove them from the pans and set them on the rack to cool completely before frosting.

While the cupcakes cool, make the frosting: In the bowl of a stand mixer fitted with the paddle attachment, mix the butter on medium speed until smooth. Add the confectioners’ sugar and salt and mix on low speed until the sugar is moistened. Turn the mixer to medium-high and stream in the vanilla, lemon juice and 1 teaspoon heavy cream. Mix until light and fluffy, about 5 minutes, adding more cream as needed to make a smooth and easily spreadable frosting.

Frost the cupcakes, top with sprinkles if desired, and serve. The cupcakes and frosting can be made and stored separately one day ahead of time, covered, at room temperature.