In a large mixing bowl, whisk together the flour, sugar, baking powder, salt, and any spices if using.
In a separate bowl, lightly whisk together the oil, egg, vanilla extract, milk, vegetable or fruit base, and any extracts, juices, and/or zests if using until well combined.
Pour the wet ingredients into the dry ingredient bowl.
Stir with a spoon or silicone spatula until just combined. This should only take about 30-45 seconds of mixing. The batter will be pretty thick and lumpy. Do not over-mix or the bread will become tough.
If using any solid mix-ins, gently fold them into the batter.
Divide the batter evenly between the muffin cups, leaving about ½-inch from the top, or pour into your loaf tin. If using, sprinkle the sugar or streusel topping liberally on each muffin or on top of your loaf.
Bake at 350°F (175°C) for 60-70 minutes until lightly golden brown and the tops spring back when gently pushed or a toothpick inserted in the center comes out clean. Check on your bake at about the halfway mark, and if it looks as though it is not baking evenly, rotate the pan.
Transfer the baked loaf out of the pan onto a cooling rack about 10 minutes after taking it out of the oven. Let it cool completely before glazing.
Store uneaten bread covered in foil or plastic wrap at room temperature for up to 3 days.