Add the 2 tablespoons of flour to a plate. Lightly coat each biscuit in flour and shake off the excess.
Keep each biscuit flat and divide each biscuit into 4 strips, rotate, then divide across into 3 rows to create about 12 small pieces. Repeat with the remaining biscuits and set aside.
Season the chicken breast with salt and pepper.
Heat the cooking oil in a Dutch oven or large pot over medium-high heat. Sear the chicken until golden on both sides without cooking it completely through. Remove the chicken and set aside to cool slightly.
Reduce the heat to medium and add the frozen mixed vegetables. Stir as they release moisture, using it to loosen the browned bits from the bottom of the pot.
Add the garlic powder, onion powder, poultry seasoning, and black pepper. Cook until the excess water from the vegetables has evaporated and they begin to pick up a little color.
Add the butter. Once melted, stir in the ⅓ cup flour and cook for about 1 minute.
Increase the heat to medium-high and pour in the chicken broth. Crumble in the chicken bouillon cube and stir occasionally as the broth comes to a simmer and begins to thicken.
Cut the seared chicken into bite-size pieces and add it to the broth.
Add the cut biscuit pieces gradually, stirring between additions. The dumplings will initially float and the pot may look crowded, but they will settle as they cook.
Pour in the evaporated milk and stir.
Once the broth returns to a simmer, reduce the heat to medium-low and simmer for about 15 minutes, until the chicken is cooked through and the biscuit dumplings are cooked.
Turn off the heat and allow the chicken and dumplings to cool slightly before serving.