Preheat oven to 375 degrees Fahrenheit.: You will notice the kitchen warming as the oven comes to temperature and a small dry heat that encourages browning. This step matters because an oven at the right temperature helps the muffins rise quickly, setting tender domes while creating a lightly crisp top. A common mistake is skipping preheat, which can result in flat, dense muffins, so always wait until the oven reads steadily. When the oven clicks and the air smells faintly toasted, you are ready.
Butter nine cups of a 12-cup standard-size muffin pan, or spray with nonstick cooking spray.: Greasing the pan ensures the muffins release easily and keeps edges from sticking and tearing. As you grease, run your finger along each cup to feel for full coverage, then give a careful tap to remove excess. If you under-grease, muffins can cling to the pan and break when removed, so take the extra second to coat thoroughly. The slightly shiny surface after greasing is a good visual cue that you are set.
In a large bowl, whisk together the flour, sugar, baking powder, and salt.: You will smell the subtle sweetness as you combine ingredients and see a pale, uniform mixture forming. This dry blend distributes the leavening so every muffin lifts evenly, which is why whisking until homogeneous is important. Overworking the dry mix is not a worry here, but if you see pockets of baking powder, whisk longer. A common error is adding liquids before fully mixing dry ingredients, which can cause uneven rise.
In a medium bowl, whisk together the ricotta cheese, orange zest, orange juice, olive oil, and egg until well-blended.: The aroma of fresh orange will intensify as you whisk, and the texture will go from lumpy to smooth and slightly glossy. This step creates an emulsion that suspends fat and liquid for a cohesive batter, which is why thorough whisking matters. If the ricotta cheese seems grainy, whisk longer to smooth it out; otherwise you may get uneven pockets of dairy in the muffins. Avoid overbeating, which can aerate the mixture too much.
Make a well in the center of the dry ingredients, and pour in the wet. Stir with a wooden spoon until just incorporated. The batter will be thick.: At this point, you will notice a contrast in textures, the pale dry mixture and the glossy wet center. Folding gently avoids developing gluten, preserving a tender crumb. Stir until you can no longer see streaks of flour, but expect a thick consistency; this thickness is what creates sturdy domes. A common pitfall is overmixing, which yields chewy muffins, so stop when combined.
Divide batter evenly between the nine muffin cups, about 1/3 cup each (note: you can go ahead and make 12 muffins instead of the nine, but they will be flatter and smaller).: you can go ahead and make 12 muffins instead of the nine, but they will be flatter and smaller). : As you scoop, you will feel the weight and density of the batter, and the tops will sit slightly mounded. Even distribution ensures uniform baking and consistent texture across the batch. If portions vary wildly, some muffins will brown faster and may dry out. Use a scoop or a measuring cup for steady portions to avoid underfilled or overflowing cups.
Bake for about 15 minutes, or until a toothpick inserted into the center comes out clean (not wet).: During baking, the kitchen will fill with citrus perfume and you will see the tops turning a light golden color, possibly cracking slightly as they rise. The toothpick test is your best cue for doneness; when it emerges clean the interior has set without being overbaked. Leaving them in a minute or two too long can dry the crumb, so check at the earlier end of the time range if your oven runs hot.
Remove from oven and set pan on a wire rack. Let cool for five minutes, then remove muffins and set on a wire rack set over a layer of paper towels (to catch any glaze overflow).: The initial cool time lets the structure settle so muffins release cleanly from the pan; you will notice steam easing away. Moving them to another rack helps the bottoms stay crisp rather than steaming on a hot tray. If you rush this step and try to glaze too soon, the tops may be so hot the glaze runs off; wait the five minutes for optimal adhesion.
In a small saucepan over medium-low heat, warm the half-and-half and rosemary just until steaming. Remove from heat, cover, and let sit for 10 minutes. Strain and discard solids. Add liquid to a small bowl, then sift in powdered sugar. Add orange zest and a pinch of kosher salt. Whisk until smooth. With a spoon, drizzle glaze over the top of the muffins. Drop a fresh rosemary leaf or two on top of each one. Glaze will harden a bit after sitting.: As you warm the half and half , the kitchen will carry a fragrant herbal note as rosemary releases its oils; the steaming point is enough to extract flavor without boiling away delicate aromas. Straining produces a clear infusion for a silky glaze, and sifting the powdered sugar prevents lumps for a glossy finish. When you drizzle, watch for the glaze to cling and set slightly, forming a thin shelliness that adds textural contrast. A common mistake is overheating the cream, which can deepen the herbal flavor too much or scald the dairy, creating an off note.
The keep in an airtight container at room temperature for up to three days, or freeze in a zipper bag for up to three months.: You will notice that at room temperature the muffins remain tender and the glaze keeps a slight sheen; storing airtight preserves moisture and prevents staling. Freezing halts any loss of freshness, and reheating gently in a low oven revives the texture. Avoid leaving them uncovered, as they will dry out and the glaze can collect a sticky film.