Preheat the oven to 180 C / 360 F.
Grease the inside of the bundt pan with butter, and cover the upper half with parchment paper, extending a few inches above the pan. Brush the paper with oil. Set the pan aside.
Into a bowl, sift the flour and salt. Set the bowl aside.
Add eggs to the bowl of a stand mixer. Using the whisk attachment, turn the mixer to high, and beat the eggs for 5 minutes.
Start adding the sugar gradually, 2-3 tbsp at a time. Beat for another 5-7 minutes on high, or until the mixture is pale and thick. If you create a swirl using the whisk, its shape should hold.
Attach the paddle attachment, and turn on the mixer to medium-low speed. Gradually fold in the flour. Mix the batter one last time using a spatula to make sure that all the flour is incorporated and there are no lumps.
Pour the batter into the prepared pan. Bake for 30-35 minutes, or until an inserted toothpick comes out clean.
Let the cake cool for 10-15 minutes on the countertop at room temperature. The cake will deflate a little bit, which is totally fine.
Run a spatula around the cake to make sure no sides are sticking. Flip onto a large plate.
Sprinkle powdered sugar and cinnamon on top for garnish.