Place oil in a large Dutch oven and heat over medium-high.
Remove the biscuits from the can. Using a small circle cookie cutter, remove the centers from each biscuit, reserving the center cut-outs to fry for donut holes.
Once the oil has reached a temperature of 350°F, and while working in batches, fry the donuts for about 2 minutes per side or until deeply golden and cooked through.
Using a slotted spoon, remove the donuts from the oil, and set aside to drain on a wire rack.
Fry the center cut-outs for 1-2 minutes, turning occasionally to evenly brown. Using a slotted spoon, remove the donut holes, and set aside to drain with the full-sized donuts.
Place the sweetened condensed milk in a shallow bowl. Dip the donuts and donut holes into the sweetened condensed milk coating the tops, return to the wire rack to cool and for the glaze to firm up slightly.
For a chocolate glazed donut, pour the chocolate fudge sauce into a shallow bowl. Dip the donuts into the sauce, letting any excess fudge drip off before inverting and returning to the wire rack to set.
To make a peanut butter glaze, combine 1/4 cup of creamy peanut butter with 1/4 cup sweetened condensed milk, and 2-4 tablespoons of whole milk. Whisk until smooth, and glaze-like in thickness. Depending on the peanut butter, you may need to add more or less milk. Dip the donuts into the sauce, letting any excess peanut butter glaze drip off before inverting and returning to the wire rack to set.