Place blueberries and water in a small saucepan over medium-high heat. When berries start to boil, stir in agave or maple syrup and reduce to a simmer.

Mix cornstarch with the water until cornstarch is completely dissolved. Stir mixture into berries, continue to simmer an additional 2 to 3 minutes or until desired consistency is reached.

Transfer to serving or storage container, cover and set aside.

While berries are simmering, mix together Ricotta cheese, lemon juice, zest, and agave or syrup if using.

Spread toast with Ricotta, top with berries and garnish with mint.