Preheat oven to 300°F (150°C). Line the bottom of a 6" cake pan with parchment paper and grease the sides.
Boil 2 inches of water in a small saucepan over medium heat. Lower the heat to a simmer.
Place cream cheese and milk into a large bowl. Place that on top of the saucepan with simmering water. This will gently heat and melt the ingredients.
When ingredients are melted, add butter and mix until melted.
Remove bowl from the saucepan and place on a work surface. Add egg yolks and whisk until combined. Then add lemon juice and vanilla and whisk.
Sift in flour, cornstarch, and salt, and mix to combine. Set batter aside.
Whisk egg whites in a large bowl on high. Add ⅓ amount of sugar when bubbles start to form. Add another ⅓ of the sugar when lots of bubbles have formed. Add the remaining sugar when egg whites are frothy. Then whip to soft peaks.
Fold ⅓ of egg whites into the cheesecake batter. Fold another ⅓ egg whites into the batter, making sure to not deflate the egg whites. Fold the final ⅓ egg whites into the batter until combined.
Remove 3 tablespoons of batter into a small bowl. Pour the rest of the batter into the prepared pan.
Add food colouring to the batter in the small bowl and mix to combine. Place batter into a small piping bag or a ziplock bag. Cut the end (or corner if using a bag) and draw flowers on top (or any design you choose).
Place cheesecake pan into a larger 9 inch cake pan. Pour water in the 9 inch pan to go part way up the smaller cake pan. This makes a water bath which helps cheesecakes bake evenly and without cracks.
Bake for 60 to 70 minutes, or until cheesecake has a slight wiggle in the center. Do not open the oven door while cheesecake is baking.
Cheesecake can be served warm or cold. Store leftovers in the refrigerator for up to 3 days.