Preheat the oven to 350°F (175°C). Grease and flour an 11-inch (28 cm) tart mold, or prepare mini tart molds if you prefer.
Add all of the filling ingredients to a blender, pouring in the liquid ingredients first for the best results. Blend slowly until everything is fully mixed. Do not over blend.
Pour the batter into the mold, making sure to leave space for the sliced pear topping. The batter will barely rise when baking, but the addition of the pears will make it rise in the pan.
Cut the other three pears in thin slices to decorate the tart. I don't do this earlier so that they don't turn brown. Carefully place them around the tart, one overlapping with the next. Start with the outer ring and move inwards.
Bake the tart for 50 minutes, or until a toothpick comes out of the center completely clean. Let the tart cool on a wire rack for 30 minutes.
Meanwhile, make the glaze. Mix the apricot jam with 1 tablespoon of water, and heat until warm. Once the tart has cooled, gently brush it on top.
Unmold the cooled tart and refrigerate on a plate until you are ready to serve. Garnish with powdered sugar on top if desired, then slice and enjoy!