In a small bowl, mix the cornstarch and water until smooth.
Combine blueberries, sugar, lemon juice, and the cornstarch mixture in a saucepan over medium heat.
Bring to a simmer, stirring gently, until the sauce thickens and becomes glossy, about 5 to 10 minutes.
Remove from heat and let it cool slightly. The sauce will thicken further as it cools.
Serve the blueberry topping over cheesecake, pancakes, or as desired.
Notes
If using frozen blueberries, no need to thaw them before cooking.
• Stir the mixture gently to avoid breaking the blueberries, keeping some texture.
• Adjust the sugar according to the sweetness of the blueberries and your preference.
• Let the sauce cool down a bit before topping the cheesecake to avoid melting it.
• This topping can be made in advance and stored in the refrigerator.