In a large bowl, whisk together gluten-free flour blend, cinnamon, salt, baking powder, and sugar. Stir in melted dairy-free butter and pure vanilla extract.
Line a 9x9-inch baking dish with parchment paper. Reserve 1 scant cup of the crust for the topping. Press the remaining crust into the baking dish.
Mix together diced peaches, sugar, cornstarch, lemon juice, cinnamon, nutmeg and salt until the peaches are completely covered.
Pour the peach mixture over the crust.
Sprinkle the remaining crust dough evenly over the peach filling.
Bake at 350F for 45-50 min, until peach filling is bubbling and crust is a golden brown. Let sit for at least half an hour, until peach filling sets up completely before slicing into bars. Store in the refrigerator or freezer for best results.