Preheat the oven to 350°F. Spray a 9 inch loaf pan with baking spray, set aside. In the bowl of a stand mixer with the paddle attachment or in a large bowl with a hand mixer, cream the butter and sugar. Start on low speed until incorporated, set to medium speed and mix for 2-3 minutes until light and fluffy. The mixture will be a light color. Add in the egg, lemon zest, vanilla, and lemon juice, stir to combine, scrape down the sides as needed.