Preheat your oven to 350°F (175°C) and grease a round cake pan (8 or 9-inch works best). Line the bottom with parchment paper for easier removal.

In a large bowl, sift together the flour, baking powder, baking soda, and salt. This ensures the dry ingredients are well combined and lump-free.

In a separate bowl, whisk the eggs and sugar until pale and slightly thickened. Add in the vegetable oil, yogurt (or sour cream), vanilla extract, orange juice, and orange zest. Mix well until smooth.

Slowly fold the dry ingredients into the wet mixture, being careful not to overmix. Stir just until combined, so the cake stays tender.

Pour the batter into the prepared cake pan and smooth the top with a spatula. Bake for 30–35 minutes, or until a toothpick inserted into the center comes out clean.

Remove from the oven and allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.

For the ganache, heat the heavy cream in a small saucepan until just simmering (do not boil). Remove from heat and pour over the chopped chocolate. Let it sit for 2–3 minutes to soften the chocolate.

Stir gently with a spatula until smooth and glossy, then add the butter and mix until fully incorporated.

Let the ganache cool slightly before pouring it over the cooled cake. Spread evenly with a spatula, letting it drip down the sides for a luscious finish.

Allow the ganache to set for about 20–30 minutes before slicing and serving.