As you become experienced in cooking, you learn how to "READ" recipes. What I mean by that is, as you go through a recipe, you will note where things are arguable, or wrong (more often than you might think), where there will be problem spots, and where there will be difficulties.
The recipe under discussion was one which called for a "9x13 inch rimmed baking sheet." Now, Annalena has many pots and pans. She has 9x13 inch baking dishes (these are the standard size). But a rimmed baking sheet of this size? No. For info, if you need to know, a standard baking sheet is 13x18 inches. It's called a "half sheet", because the ones that commercial ovens use are bigger. So, of course, a 9x13 inch baking sheet, is half as long.
Go and find one. I have smaller baking sheets. I measured. Nope, they are not 9x13. So, I could have worked with the recipe, and only filled half the sheet, but I knew that wouldn't work. Bread rises, it moves, and it would have been a mess
My solution was to double the recipe. This would be more than would be necessary for a 13x18 inch pan but it would still work.
Some other things to consider. When you modify a bread recipe, as you will learn, if you double it, you do NOT double the yeast. If you do, you will get puffy, light, "feather bread," which may be what you want, but it will also lack flavor. You will also learn, with experience, that the standard ratio for a solid loaf bread, is one cup water to three cups flour. If that ratio changes, you either have very soft dough, or dough that will bake up like a brick. "Artisanal" breads are wetter, as are pizza doughs and, as we will see, focaccia.
Also, you will learn that you can substitute things if they have the same "feel." This recipe calls for pears. Don't care for them? Don't have them? Use apples. Or, use crips persimmons. Or, if you want to go the vegetable route, a chayote squash. No blue cheese? Try fontina. Or feta. There are no herbs in the recipe. Wanna try them? Work them into the dough.
This is a good recipe. Make it, and then play with it. Here we go.
Start with 2 cups of water. We all live in homes that are overheated, so don't worry about warm water. Combine it with a tablespoon of yeast. That's a package, if you use the little yellow red ones you can get at the supermarket . CHECK THE EXPIRATION DATE AND IF YOU BUY YEAST, PUT IT IN THE FREEZER TO KEEP IT ALIVE. One teaspoon of a sweetener of some kind: sugar, honey, maple syrup, whatever. Combine all of this together with a cup of olive oil. Add 2 cups of flour, just all purpose unbleached. Stir it, and let it sit for ten minutes. Then add the rest, use whatever you use to knead bread, and let it sit, for one hour, while you get the rest of the ingredients ready.
Which are... 2 onions, sliced in half moons, 2 pears, sliced thin (or the substitutions above), and a generous cup and a half of crumbled cheese.
Cook the onions in a few tablespoons of olive oil. Cook them slowly, for ten minutes in a covered pan. Then take off the cover, and cook them for another ten minutes. Or, if you get to a nice brown finish in less time, STOP.
While the bread is rising, preheat your oven to 450. Lightly grease a 13x18 inch baking pan with some olive oil, and spread the dough out over it. It will resist a little. Let it rest, and then push it some more. Then keep repeating until you have the pan covered. It will take some time, but it will get there. Then, dimple it, and let it sit for 20 minutes.
The dimpling is important for focaccia. it gives the filling a chance to settle in a nook, and cook unevenly, which is something you want.
Ok, let's assemble. After twenty minutes, drizzle a couple of tablespoons of olive oil over the bread, sprinkle the cheese, spread out the onions, and lay out the slices of fruit. Get this in the oven and bake it for 20 minutes. Or longer, if you want a darker pan of bread. Let it cool, and serve it forth, maybe with the vignarola soup we just made.
Focaccia doesn't keep well. Eat this either the day you make it or at the latest, the day after. And after you make it the first time, play with the ingredients. Leeks instead of onions? Apples instead of pears? Cheddar or fontina instead of blue? You're the boss. To paraphrase my first trainer "control the ingredients, don't let the ingredients control you."