Preheat oven to 350°F (175°C).

Prepare a 10-cup bundt pan by spraying with cooking oil and dusting with flour.

Cream together sugar and softened butter until light and fluffy.

Whisk together cornstarch and water to form a slurry.

Add the cornstarch slurry to the creamed sugar and butter mixture and mix well.

Stir in milk and lemon extract (or lemon juice).

In a separate bowl, combine flour, baking powder, and baking soda.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Gently fold in the blueberries.

Pour the batter evenly into the prepared bundt pan.

Bake for 45 minutes, or until a cake tester inserted into the center comes out clean.

Let the cake cool in the pan on a wire rack for 30 minutes.

Invert the cake onto a serving plate or pedestal.

Prepare the glaze by placing powdered sugar in a small bowl.

Add lemon juice one tablespoon at a time, stirring until you reach the desired glaze consistency.

Spoon the glaze evenly over the warm cake.

Garnish with lemon zest and fresh blueberries (optional).