Gather all of the ingredients and equipment so that you can work quickly once the plant milk and vegan butter are out of the refrigerator. Keep them cold until just before you need them. This helps keep the ladyfingers light and airy.
Stir the cold plant milk and apple cider vinegar together. Set it aside for 2-3 minutes to give it time to curdle. Preheat the oven to 350°F (177°C). Line 1 large or 2 smaller baking sheets with silicone baking mats or parchment paper.
Beat the cold vegan butter and cane sugar together in a large bowl until it forms a grainy texture. Next, beat the buttermilk and vanilla into the mixture until everything is fully combined.
Use a sifter to add the flour, baking powder, and salt to the bowl. Beat them in just until they’re fully combined. The batter will be smooth and thick.
Spoon the batter into a piping bag. Pipe the batter in strips that are 2 1/2 inches long and an inch apart from each other.
Bake the ladyfingers for about 10-12 mins in the middle of the oven. Start checking on them around 10 minutes and remove them as soon as you see a light golden color forming on the bottom/edges.
Let them cool on the baking sheet for 5 minutes and then transfer them to a cooling rack for another 10 minutes. Dust them with powdered sugar and enjoy! No need to add powdered sugar if you're planning to use them to make tiramisu.