Use css style

app/views/dashboard/projects/_projects.html.haml

@@ -5,6 +5,7 @@
       - if current_user.can_create_project?
         %span.input-group-btn
           = link_to new_project_path, class: 'btn btn-green' do
-            + New Project
+            %i.fa.fa-plus
+            New Project
 
   = render 'shared/projects/list', projects: @projects, ci: true

app/views/groups/_projects.html.haml

@@ -5,6 +5,7 @@
       - if can? current_user, :create_projects, @group
         %span.input-group-btn
           = link_to new_project_path(namespace_id: @group.id), class: 'btn btn-green' do
-            + New Project
+            %i.fa.fa-plus
+            New Project
 
   = render 'shared/projects/list', projects: @projects, projects_limit: 20, stars: false