The Back Abbey Recipe

Prepare and cook onions

Heat a large skillet over medium heat. Add the butter and olive oil and let the butter melt. Add the thinly sliced onions and stir to coat with fat. Sprinkle the salt and sugar over the onions to help draw out moisture and promote browning. Cook, stirring every 3–5 minutes, adjusting the heat as needed so the onions brown slowly and do not burn. Total cooking time will be about 25–35 minutes until onions are deep golden and soft.

Finish onions

If the pan becomes dry or onions begin to stick, add a tablespoon of water and gently scrape the fond from the pan. During the last 2 minutes of cooking, stir in the balsamic vinegar (optional) to deglaze and add a touch of acidity. Taste and adjust seasoning with a little more salt if needed. Remove from heat and set aside.

Make aioli

In a small bowl whisk together the mayonnaise, Dijon mustard, whole grain mustard, lemon juice, and minced garlic until smooth. Season with salt and black pepper and taste; adjust acidity or seasoning as desired. Refrigerate until ready to assemble so flavors meld (at least 15 minutes).

Cook bacon

Preheat oven to 400°F (200°C) or heat a large skillet over medium heat. Cook the Niman Ranch bacon until crisp, about 8–12 minutes in the oven on a sheet pan or 6–8 minutes in a skillet, turning as needed. Transfer cooked bacon to a paper towel–lined plate to drain.

Assemble sandwiches

Spread a generous layer (about 1 tablespoon) of the mustard aioli onto one side of four bread slices. Divide the aged Gouda evenly over the aioli on those slices. Top the cheese with a portion of the warm caramelized onions (about 2–3 tablespoons per sandwich) and then 2 slices of cooked bacon. Add a small handful (about 1/4 cup) of microgreens on top of the bacon. Close each sandwich with the remaining bread slices. If desired, spread a thin layer of butter on the outer faces of the top bread slices for grilling.

Grill sandwich

Heat a clean skillet or griddle over medium-low to medium heat. Place each sandwich seam-side down in the pan, pressing gently with a spatula or a weighted press. Cook until the bread is golden brown and the Gouda melts, about 3–4 minutes per side. If bread browns before cheese melts, cover the pan briefly (1–2 minutes) to trap heat and help the cheese melt. Alternatively, finish in a 350°F (175°C) oven for 3–5 minutes.

Serve

Transfer sandwiches to a cutting board, let rest 1 minute, then slice in half. Serve immediately with any extra mustard aioli on the side for dipping.