For the cake:

• Grease and parchment line the cake pans and preheat the oven to 350°F
• Combine the flax meal with the hot water and let stand for about 5 minutes to thicken
• Add the vinegar to the soy milk to sour
• Sift the flour with the baking powder and salt
• Cream the vegan butter with the sugar until light and fluffy and this may take about 3-5 minutes on medium to high speed
• Add the thickened flax paste while mixing on medium speed, scrape the bottom and sides of the bowl to incorporate evenly, add the vanilla extract
• Add about 1/3 of the flour to the creamed mixture then add half of the soured milk
• Add another 1/3 of the flour and then the remaining sour milk
• Add the last amount of flour and mix just to combine evenly.
• Divide the batter evenly into the 3 greased and parchment lined cake pans and bake in a preheated oven for 25-30 minutes or until springy to the touch when you gently press the centers
• Prepare the buttercream recipe according to the instructions on that recipe post and then divide it into 4 small bowls for the color decor
• Assemble the cake & decorate as shown in the video tutorial