Bake for about 8-10 minutes (if divided into 4 parts) or longer. Remove from the oven and let stand 5-7 minutes then remove and place on parchment (which I slightly sprinkled with corn starch). Let them stay at room temperature for at least 8-10 hours (I made 24 hours in advance).
Divide the butter into 3-4 equal parts and add the food coloring (use different amount of the coloring for each part).
Sift the flour, baking powder, and salt and incorporate the dry ingredients into the wet mixture. Gently stir the mixture with a spatula until just incorporated.
Add the milk, olive oil, and vanilla, and beat just until incorporated.
Cream the butter with a mixer until light and fluffy. Gradually start to incorporate the sugar (1/2 cup at once) continue beating. Add the eggs one at a time.
Preheat the oven to 170 degrees C (350 degrees F). Spray a 9 inch pan(s) with some cooking oil and sprinkle with a bit of flour.