Place cereal mix in a large heatproof bowl (you can also use the bowl of your stand mixer). Pour boiling water on top. Let the mixture cool until a digital thermometer reads about 110°F (43°C). This usually takes 20 minutes. Pay attention to the temperature because if it’s too hot, it will kill the yeast. If it became too cool, however, it’s not a problem—the dough may just take a few extra minutes to rise.

Whisk the yeast, sugar, and all of the warm water/cereal mixture in the bowl of your stand mixer fitted with a dough hook or paddle attachment. Cover and allow to sit for 5-10 minutes or until foamy and bubbly on the surface.

Add the butter, salt, and 1 cup (about 130g) flour. Beat on low speed for 30 seconds, scrape down the sides of the bowl with a silicone spatula, then add another cup of flour. Beat on medium speed until relatively incorporated (there may still be chunks of butter). Add all of the remaining flour and the seeds/nuts (if using), then beat on medium speed until the dough comes together and pulls away from the sides of the bowl, about 2 minutes. If it seems too sticky, add more flour, 1 Tablespoon at a time until it begins to pull away from the sides of the bowl. *If you do not own a mixer, you can mix this dough with a large wooden spoon or silicone spatula. It will take a bit of arm muscle!*

Keep the dough in the mixer and beat for an additional 3-5 full minutes, or knead by hand on a lightly floured surface for 3-5 full minutes. (If you’re new to bread-baking, my How to Knead Dough video tutorial can help here.) If the dough becomes too sticky during the kneading process, sprinkle 1 teaspoon of flour at a time on the dough or on the work surface/in the bowl to make a soft, slightly tacky dough. Do not add more flour than you need because you do not want a dry dough. After kneading, the dough should still feel a little soft. Poke it with your finger—if it slowly bounces back, your dough is ready to rise. You can also do a “windowpane test” to see if your dough has been kneaded long enough: tear off a small (roughly golfball-size) piece of dough and gently stretch it out until it’s thin enough for light to pass through it. Hold it up to a window or light. Does light pass through the stretched dough without the dough tearing first? If so, your dough has been kneaded long enough and is ready to rise. If not, keep kneading until it passes the windowpane test.

Lightly grease a large bowl with olive oil or nonstick spray. Place the dough in the bowl, turning it to coat all sides in the oil. Cover the bowl with aluminum foil, plastic wrap, or a clean kitchen towel. Allow the dough to rise in a relatively warm environment for 1-2 hours or until double in size. (I always let it rise on the counter. Takes about 2 hours. For a tiny reduction in rise time, see my answer to Where Should Dough Rise? in my Baking with Yeast Guide.)

Grease a 9×5-inch loaf pan.

When the dough is ready, punch it down to release the air. Lightly flour a work surface, your hands, and a rolling pin. Roll the dough out into a large rectangle, about 8×15 inches. It does not have to be perfect– in fact, it will probably be rounded on the edges. That’s ok! Roll it up into an 8 inch log and place in the prepared loaf pan.

Cover shaped loaf with aluminum foil, plastic wrap, or a clean kitchen towel. Allow to rise until it’s about 1-2 inches above the top of the loaf pan, about 1 hour. (See photo above for a visual.)

Adjust oven rack to a lower position and preheat oven to 350°F (177°C). (It’s best to bake the bread towards the bottom of the oven so the top doesn’t burn.)

Bake for 35-40 minutes– if you notice the top browning too quickly during bake time, loosely tent the pan with aluminum foil. How to test for doneness– give the loaf a light tap. If it sounds hollow, it’s done. For a more accurate test, the bread is done when an instant read thermometer reads the center of the loaf as 195°F-200°F (90°C-93°C).

Remove from the oven and allow bread to cool for a few minutes before slicing and serving. Feel free to let it cool completely before slicing, too.

Cover leftover bread tightly and store at room temperature for 2-3 days or in the refrigerator for up to 10 days.