Remove the avocado flesh from the skin, add to a bowl with the goat cheese and mash together.
Add garlic and chipotle powder.
Mix until smooth.
Spread on all 4 slices of bread.
Pile bacon on one side of each sandwich.
Add thinly sliced tomatoes and spinach.
Top with second piece of bread.
Heat a panini pan and press (see note below) over medium-high heat and brush with vegetable oil.
Place a sandwich in the pan, place the press on top and press down for about 20 seconds.
Cook for an additional 1-2 minutes, until bread is nicely toasted and spinach is slightly wilted.
Remove to a plate and repeat with second sandwich.
Note: If you dont have a panini pan you can use a regular skillet and another heavy pan as a press, or just press the sandwich down with a spatula and flip halfway through cooking.