Preheat the oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving some overhang on the long sides, and lightly grease the paper with canola oil.
Spread the rolled oats, chopped almonds, and sunflower seeds in an even layer on a large baking sheet. Toast in the preheated oven, stirring once halfway through, until lightly golden and fragrant, 8–12 minutes. Transfer the mixture to a large heatproof mixing bowl and reduce the oven temperature to 325°F (165°C).
While the oats and nuts toast, combine the honey, light brown sugar, unsalted butter, fine sea salt, vanilla extract, and ground cinnamon in a small saucepan.
Set the saucepan over medium heat and cook, stirring often, until the butter melts and the sugar fully dissolves and the mixture just begins to bubble around the edges, 3–4 minutes. Remove the pan from the heat.
Pour the warm honey mixture over the toasted oats, almonds, and sunflower seeds in the mixing bowl. Stir thoroughly with a spatula until all of the dry ingredients are evenly coated and no dry patches remain.
Add the chopped dried cranberries and mini chocolate chips to the bowl. Stir quickly and gently until the mix-ins are evenly distributed; if the mixture is very hot, let it cool 2–3 minutes before adding the chocolate chips so they do not fully melt.
Transfer the granola mixture to the prepared 9×13-inch pan. Spread it into an even layer, then press it down very firmly with a spatula or the bottom of a measuring cup, paying special attention to the corners and edges so the mixture is tightly compacted.
Bake the granola mixture at 325°F (165°C) until the top looks lightly set and just starting to turn golden at the edges, 15–20 minutes. The bars will still feel soft but will firm as they cool.
Place the pan on a wire rack and let the granola cool completely in the pan, at least 1–2 hours, until firm to the touch and no longer warm.
Use the parchment overhang to lift the cooled slab out of the pan onto a cutting board. With a sharp knife, trim the edges if desired, then cut the slab into 16 bars or squares.
Store the granola bars in an airtight container at room temperature, with parchment between layers to prevent sticking, for up to 5 days, or refrigerate for a firmer texture for up to 2 weeks.