Preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper for easy clean-up.
Then arrange the keto tortillas in a single layer on the baking sheet. Lightly brush each tortilla with olive oil for added crispiness. Bake in the preheated oven for 10 minutes until they reach a desirable crispness.
Next, in a mixing bowl, combine the shredded chicken, chili powder, cumin, oregano, paprika, diced green chilies, salsa, and finely chopped jalapeño pepper. Stir the mixture thoroughly to ensure the chicken is well-coated with the spices and other ingredients.
Remove the crisped tortillas from the oven. Spoon an even layer of the chicken mixture onto each tortilla, spreading it to cover the surface.
Generously sprinkle Fiesta blend cheese over the chicken layer on each tostada.
Return the tostadas to the oven and bake for an additional 5-10 minutes or until the cheese is melted and bubbly.
Before serving, garnish each tostada with freshly chopped Roma tomatoes and green onions. Serve hot, and enjoy a burst of flavor in each bite.