In a large mixing bowl, whisk together the flour, baking powder, and salt until combined. Create a well in the center, melt the vegan butter, and pour it into the well along with the dairy-free milk. Mix until a dough forms, then knead gently on a floured surface for about 5 minutes until smooth. Wrap the dough in plastic wrap and chill for 30 minutes to firm up.

While the dough chills, thaw the spinach and squeeze out excess moisture. In a skillet over medium heat, add a splash of olive oil and sauté the chopped onion and minced garlic until they soften and become fragrant, about 4-5 minutes. Stir in the spinach and seasonings, cooking for another 2-3 minutes before removing from heat. Let it cool, then fold in the vegan cheese.

Once the dough has chilled, preheat your oven to 392°F (200°C) and line a baking tray with parchment paper. Roll out the dough to about 1/8-inch thickness and cut out circles. Place 1-2 teaspoons of filling in the center of each circle. Fold the dough over to create a crescent shape and seal the edges with a fork.

Brush the top of each assembled empanada with olive oil and soy milk. Arrange them on the baking tray, leaving space between each one. Bake for approximately 20 minutes, or until golden brown and flaky. Allow to cool slightly before serving.