Blueberry Lattice Pie

• 9 pyrex pie (pan)
• 5 blueberries (rinsed)
• 2 crust pie filling
• 1 lemon zest (finely grated)
• 240 ml blueberries with the sugar in a nonreactive saucepan
• 150 gr sugar
• 45 ml water
• 24 gr cornstarch
• 18 gr butter (unsalted)
• 4 gr sugar for finishing the top