Prepare the Perfect Vanilla Cheesecake as per the recipe instructions and let cool completely. Then, refrigerate for 2 hours.
Make the topping following this recipe with 3 tablespoons of sugar. Place 1 ½ cups raspberries in a small saucepot, cover and simmer until the juices come out. Add sugar and lemon juice and simmer for 3-5 minutes until glossy and cooked down into a jammy consistency.
Combine corn starch with water and stir it into the berry mixture. Cook until it comes to a gentle boil while stirring and let bubble for about 20 seconds. Remove from heat and stir through the additional ½ cup of fresh raspberries. Pour it into a clean jar and set aside to cool completely before serving over the chilled cheesecake.