Before starting, preheat the oven to 450°F. Wash and dry all produce. Cut bacon crosswise into 1/4-inch strips. Heat a large non-stick pan over medium-high heat.When hot, add bacon. Cook, flipping occasionally, until crispy, 5-7 min.** (TIP: Reduce heat to medium if bacon is browning too quickly!)Remove the pan from heat. Using a slotted spoon, transfer bacon to a paper towel-lined plate. Set aside. Reserve bacon fat in the pan.

Meanwhile, quarter potatoes. Add potatoes, 2 tsp salt and enough water to cover (by approx. 1 inch) to a large pot (use same for 4 ppl). Cover and bring to a boil over high heat. Once boiling, reduce heat to medium. Simmer uncovered until fork-tender, 10-12 min. Drain and return potatoes to the same pot, off heat. Cover to keep warm.

Meanwhile, combine breadcrumbs and 1 tsp (2 tsp) oil in a small bowl.Combine cheddar cheese, cream cheese and bacon in a medium bowl. Carefully slice into the centre of each chicken breast, parallel to the cutting board, leaving 1/2 inch intact on the other end. Cover each chicken breast with plastic wrap. Using a mallet, rolling pin or heavy-bottomed pan, carefully pound each chicken breast until 1/2-inch thick. Season with salt and pepper. Top one side of each chicken breast with filling, then fold the other side over filling to enclose.

Heat the pan with reserved bacon fat (from step 1) over medium-high. When hot, add chicken. (NOTE: Don't overcrowd the pan; sear chicken in 2 batches, if needed.) Sear, keeping each breast closed, until golden, 2-3 min per side. Transfer to a parchment-lined baking sheet. Spread Dijon over tops of chicken, then sprinkle with breadcrumb mixture, pressing down gently to adhere. Bake in the middle of oven until chicken is cooked through, 12-14 min.**

Meanwhile, trim ends off broccolini, then cut any larger stalks in half lengthwise, leaving thinner stalks whole. Thinly slice green onions. Halve tomatoes.Carefully discard any remaining bacon fat in the pan, then wipe clean. Reheat the same pan over medium-high. When hot, add broccolini, tomatoes and 1/4 cup (1/2 cup) water. Season with salt and pepper. Cook, tossing occasionally, until tomatoes soften and broccolini is tender-crisp, 5-6 min. Remove from heat. Add half the green onions, then toss to coat.

Roughly mash sour cream, remaining green onions, 2 tbsp (1/4 cup) milk and 2 tbsp (1/4 cup) butter into potatoes until slightly mashed. (NOTE: 'Smashed' potatoes will still have a few chunks!) Season with salt and pepper, to taste.Divide chicken, mash and veggies between plates.