Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9x13-inch baking dish.
Whisk milk, eggs, and oil together in a small bowl until smooth.
Whisk rice flour, brown sugar, and baking powder together in a large bowl. Add milk mixture; mix under batter is well-combined and creamy. Pour batter into baking dish. Sprinkle cranberries and pecans on top.
Bake in the preheated oven until firm, about 1 hour 10 minutes. Remove from oven and place on a wire rack to cool, about 30 minutes. Cut into 48 pieces.