Preheat the oven at 170ºC/ 340ºF conventional oven and prepare a 3x 20 cm (8 inch) cake pans lined with parchment paper.
In a large mixing bowl, sift all-purpose flour, baking powder, baking soda and salt. Then add granulated sugar and mix it together so everything has been combined.
330 g all-purpose flour, ¾ teaspoon baking powder, ¾ teaspoon baking soda, ¾ teaspoon salt, 225 g granulated sugar
Then add the butter and with a hand mixer or in a stand mixer, using the paddle attachment, mix it together until the butter has coated the dry ingredient and it looks like a sandy texture.
125 g butter
Then add the eggs, Greek yogurt, lemon zest, lemon juice, oil and vanilla extract and with the electric mixer mix it all together until smooth. It is a thick batter.
1 tablespoon lemon zest, 3 eggs, 225 g Greek yogurt, 40 g vegetable oil, 1 tablespoon lemon juice, 1 teaspoon vanilla extract
Mix together the blueberries and cornstarch. Add ⅔ of the blueberries and gently fold them in using a rubber spatula.
200 g blueberries, 1 teaspoon cornstarch
Divide the batter in the 3 baking pans and sprinkle with the remaining blueberries. Bake them for 20-22 minutes or until a cake tester comes out clean.
Let the cakes cool on a cooling rack. After 5 minutes, gently remove the cakes from the cake tins and let the cakes cool down completely.