In a casserole, mix blueberries with sugar and water. Cook at low heat 15 minutes, until fruits melt.
In a small bowl, dilute cornstarch in 45 ml (3 tablespoons) of water added to the blueberry mixture. Continue cooking and stirring until it thickens. Remove from heat and cool down.
Preheat oven to 350°F (180°C).
In a bowl, mix flour with butter and pecans. Spread and press the mixture into the bottom of a 33 cm x 23 cm x 5 cm (13 inches x 9 inches x 2 inches) mould.
Oven bake for 20 minutes. Remove from the oven and cool down over a grill.
With an electric mixer, whisk the cream until it forms firm peaks. In another bowl, always with the electric mixer, whisk cream cheese with sugar. Add whipped cream to the cheese mixture with a spatula, then lay over cold crust.
Pour the blueberry mixture over the cheese mixture. Refrigerate for 2 hours. Cut into 16 squares.