Preheat your oven to 350°F (175°C). Line a 9x5-inch loaf pan with parchment paper, leaving some overhang for easy removal.
In a large bowl, whisk together flour, baking soda, baking powder, cinnamon, nutmeg, cloves, and salt until well combined.
In a separate medium bowl, whisk together the melted coconut oil, maple syrup, plant milk, apple cider vinegar, and vanilla extract. The vinegar will slightly curdle the plant milk—this creates a buttermilk-like effect.
Pour the wet ingredients into the dry ingredients and stir just until combined. Avoid overmixing—about 10-12 folds should do it. Some small lumps are fine.
Fold in the diced apples, distributing them evenly throughout the batter. For extra flavor, you can toss your diced apples in 1/2 teaspoon cinnamon before adding them.
If using the streusel topping, combine all streusel ingredients in a small bowl. Use your fingers to work the vegan butter into the dry ingredients until crumbly.
Pour the batter into the prepared loaf pan and spread it evenly. If using streusel, sprinkle it over the top.
Bake for 55-60 minutes, or until a toothpick inserted into the center comes out clean with a few moist crumbs. Tent with foil after 40 minutes if the top is browning too quickly.
Allow the bread to cool in the pan for 15 minutes before transferring to a wire rack to cool completely.