Preheat your oven to 375°F (190°C). Line a loaf pan with baking paper.
Mix baking soda with yogurt in a bowl, then set it aside until small bubbles appear.
In a large bowl, beat the eggs with oil.
Add the yogurt and salt to the egg mixture, then stir it well.
Chop or process the spinach until you have small pieces (no over-blending, please!), and add it to the batter mixture. Stir well.
Add half of the flour and cornmeal to the spinach mixture with half of the poppy seed, sesame seed, and garlic powder. Stir well. Then add the rest of the flour and mix until you get a not-very-thick homogeneous mixture.
Now, add in the crumbled feta and chopped blue cheese. Give it another good stir.
Pour the mixture into the loaf pan, and sprinkle the remaining poppy and sesame seeds on top. Place it in the oven, ensuring the rack is in the middle. Bake for 30 minutes or until it's a glorious golden brown. To be sure it's done, poke it with a toothpick. If it comes out clean, you're good to go!
Cool the loaf in the pan until warm before removing and slicing.
