Preheat oven to 350 degrees F, and melt butter in 13 x 9 inch baking dish.
In medium-size mixing bowl, whisk together flour, 1½ cup sugar, baking powder, and salt.
Peel, pit, and slice peaches, then gently stir in lemon juice, almond extract, and remaining ½ cup sugar. (Adjust amount depending upon how sweet the peaches are.)
Add milk and vanilla to dry ingredients, and stir just to moisten. Pour batter into butter, and gently swirl together. Top with peaches, but do not stir.
Bake at 350 degrees for 45-55 minutes or until crust is golden. Cool on wire rack, and serve warm or cold, topped with whipped cream or vanilla ice cream.