Preheat & Prep Pan Heat oven to 350 °F (175 °C). Grease and sugar-coat or line a 9×5″ loaf pan.
Mix Dry Ingredients Whisk together flour, baking soda, baking powder, cinnamon, salt. Set aside.
Cream Butter & Sugar Beat butter and sugar until light and fluffy (~2–3 min).
Add Molasses & Spices Mix in molasses, grated or ground ginger, then eggs one at a time.
Combine Batter With mixer on low: add half dry ingredients, then sour cream-oil-water mix, then the rest of dry. Stir until just combined.
Bake Pour into pan, smooth top, sprinkle with extra sugar. Bake 50–55 min, until toothpick shows a few moist crumbs. Tent with foil if browning too fast.
Cool & Serve Let cool in pan 10 min, transfer to rack. Slice once fully cooled.