In a large mixing bowl, combine 3-1/2 c. Flour with baking powder, baking soda, salt, and spices; whisk to blend. Set aside.

Combine the eggs and sugar in large bowl of food processor. Process until pale yellow and slightly thickened. Add 1/4 c. Of melted butter and sour cream; blend well. Add dry ingredients; beat until a moist, stiff dough is formed.

Turn out onto a lightly floured surface. Knead gently, working in additional flour to prevent sticking. Dough should be soft and smooth. Cover; let rest for 30 minutes.

Preheat oven to 425 degrees Fahrenheit (400 if using convection). Generously grease 2 baking sheets (I use nonstick baking sheets without additional grease).

Roll the dough to a 1/2" thickness and cut out with 2-1/2" doughnut cutter. Transfer to the prepared baking sheets, ensuring that you leave at least 1" between doughnuts. Brush with the remaining 1/4 c. Melted butter.

Bake 12-15 minutes, or until lightly browned. Transfer to a cooling rack.

When doughnuts are completely cooled, combine the confectioners' sugar, water, and maple syrup in a small bowl. Blend until smooth, then spread over the surface of each doughnut.

Serve immediately.