Preheat oven to 400 degrees F. Whisk together the flour, sugar, baking powder and salt in bowl. With a pastry cutter, 2 forks, or your fingers, cut in the butter until flour mixture is like course crumbs. Combine egg, milk and vanilla in another bowl. Add to the dry ingredients and mix well. Transfer to a floured surface and gently knead into a smooth ball. Set aside 1/3 of the dough. Roll remaining dough into 10 to 12-inch a circle. Carefully lift and place on a non-stick or parchment-lined baking tray. Spread jam over top, leaving a 1-inch border. Fan pear slices over the jam. Brush pears with lemon juice. Roll remaining dough into a 10 to 12-inch circle. Cut into 1/2-inch wide strips. Carefully form strips into lattice top diagonally over jam and pear-topped dough. Bake for 25-30 minutes. Cool on a baking rack. Serve at room temperature.