In the large bowl of a stand mixer, whisk the flour, yeast, baking powder, ground flax seed and fennel seed together. Clip the bowl into the mixer stand and fit the mixer with the dough hook.
Check that the water temperature registers about 120 degrees on an instant-read thermometer. (In order for this type of yeast to grow, the liquid needs to be between 115 and 125 degrees.)
With mixer on medium-low speed, slowly pour the water into the flour and mix until the flour is completely incorporated. Add the salt, honey and melted butter. Increase the speed to medium and beat until the dough is smooth and pulls away from the bottom and sides of the bowl, about 6 minutes. Don’t venture too far away while it’s mixing as the mixer might dance around on the counter.
Scoop up the dough and shape it into a ball. Lightly grease the bottom and sides of the mixing bowl with olive oil, and place the dough back into the bowl. Cover the top securely with plastic wrap. Let the covered dough rise in a warm spot until doubled in size, about 45 minutes (see Cook's Notes).
Generously oil an 8-inch round cake pan with oil (I used olive oil). Turn the dough out onto a clean work surface. There’s not much need to flour—the dough is soft but not sticky. If you feel you need a little, just lightly flour your hands. Press the dough to deflate it. Shape the dough into a 7-inch-diameter round (boule) and place it, smooth side up, in the center of the prepared pan. Generously brush the top and sides of the dough with additional oil, using your hands.
Let the dough rise (no need to cover it) in a warm spot until doubled in size, about 25 minutes. It will fill the pan.
About 15 minutes before the dough is ready to bake, position a rack in the middle of the oven and preheat the oven to 375°F. When the dough has risen to about 2 inches above the edge of the pan, place the cake pan in the oven and bake until the boule is well browned and sounds hollow when tapped, about 40 minutes.
If you want a crusty crust, spritz the sides of the hot oven with water 3 times in the first 10 minutes of baking. Alternatively, you can place a pan in the bottom of the oven and fill it with ice water (with the ice cubes) immediately after placing the boule in the oven. The steam created by either of these methods promotes a crusty crust.
Transfer the pan to a rack and tip the baked bread onto a rack and remove the pan. You may need to use a sharp knife to separate the bread from the sides of the cake pan, but the bread should easily release. Set it right side up and let cool completely before eating, no matter how tempting it is.