Start by preheating the oven. Preheat with rack in the middle, until it reaches 350°F.
Brew Earl Grey tea using 1 tea bag (or 1 teaspoon of loose tea). You'll need ¼ cup of tea.
Remove from fridge Greek yogurt and eggs. Separate the egg whites from the yolk, and gather and measure all the remaining ingredients plus baking pan.
After oven has preheated, start putting together the batter.
Whip the egg whites. It needs to be whipped until medium peaks.
In a medium bowl, add all-purpose flour, baking powder and salt, and stir to combine.
In a large bowl, add egg yolks, sugar, brewed Earl Grey and vanilla (or Earl Grey) extract. Mix until combined. Add Greek yogurt, oil and Earl Grey leaves, stirring until well mixed.
Add the flour mixture and stir just until combined. Do not overmix for a lighter and fluffier cake. Some lumps are fine.
Fold the whipped egg whites into the batter. Start by folding ⅓ of it, and after incorporated, fold the remaining.
Grease with oil and dust with sugar a large bundt cake pan, and pour the batter in.
Bake for 30 to 35 minutes, or until lightly golden at the top. To check for doneness, insert a toothpick in the middle: if it comes out with some crumbs or clean, cake's ready.
Let it cool for 5 minutes before removing from the pan. Don't let it cool completely, though, or it might not come out of the bundt pan.
For the glaze, wait until cake has cooled, or wait for at least 30 minutes.
Brew Earl Grey tea with water or milk, and melt the butter.
In a medium bowl, add powdered sugar. Stiff to avoid any lumps, specially if powdered sugar was open before this recipe, as it can absorb moisture and create little lumps.
Add butter and tea, and whisk until homogeneous.
Pour glaze over the cake.