Preheat oven to 350 degrees. Line a 9-inch loaf pan with parchment paper and coat with nonstick cooking spray.
To make vegan buttermilk, in a small bowl whisk together almond milk, lemon zest, and 1 tablespoon lemon juice. Set aside to blend for 5 minutes
Meanwhile, whisk together sugar and olive oil in a large bowl until creamy. Whisk in buttermilk mixture.
In a medium bowl, combine flour, baking soda, and salt. Fold into buttermilk mixture and stir until just incorporated.
Pour batter into prepared pan and smooth the top. Bake until a toothpick inserted comes out clean with a few crumbs attached, about 45 minutes.
Remove from oven and cool at least 10 minutes in the pan. Remove to a cooling rack set over a baking sheet and cool completely.
To make the glaze:
Whisk together remaining powdered sugar, lemon juice, and vanilla until smooth. Pour over cooled cake, allowing excess to drip off the cake onto the baking sheet beneath.
Unsweetened almond milk: This works one-for-one as a substitute for regular cow's milk in this and nearly any baking recipe. Here, I combine the plant-based milk with lemon juice to create a vegan buttermilk replacement. (In case you missed it, here's my non-vegan buttermilk swap!)
Turbinado sugar: This sweetener is less processed than regular granulated sugar. The latter may or may not be vegan, depending on the brand and how its processed, so I formulated this olive oil cake recipe to use partially-refined turbinado. Some of the molasses from the sugarcane remains in the mix for turbinado sugar, so it has a subtle caramel flavor that plays nicely in this vegan dessert recipe.
Olive oil: No need to splurge on the super-fancy and flavorful olive-green finishing oils. Mild-flavored, light olive oil is ideal for baking.
Yield: My Lemon Olive Oil Cake recipe makes eight generous slices.
Storage: Store leftovers in an airtight container at room temperature for up to 4 days.
Freezer: The cooled loaf (frosted or unfrosted) can be wrapped in a double-layer of freezer plastic, dated, labeled, and frozen for up to 3 months. Thaw at room temperature.